JP2012174931A - Backside protective film for solar battery, and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backside protective film for a solar battery which has a dark-colored appearance, and is excellent in its photoelectric conversion efficiency when receiving solar light or the like on its surface, colorability, formability, heat resistance, flexibility, incombustibility, and adhesion with a member containing an ethylene-vinyl acetate copolymer, and to provide a solar battery module.SOLUTION: A backside protective film for a solar battery according to the invention is a laminate film which comprises, in turn: a layer (A-layer) (11) including an infrared-transmissive coloring agent mixture consisting of at least two kinds of coloring agents, and a rubber-containing aromatic vinyl resin; a layer (B-layer) (12) including titanium oxide having an average primary particle diameter of 0.24 μm or larger, and a rubber-containing aromatic vinyl resin; a layer (C-layer) (13) including a saturated polyester resin; and a layer (D-layer) (14) including a fluorine resin. With a surface of the laminate film on the side of the A-layer irradiated with light of a wavelength of 740 nm, the reflectance of the light is 20% or larger.

Description

  The present invention relates to a solar cell back surface protective film and a solar cell module that have a dark color appearance and are excellent in photoelectric conversion efficiency when irradiated with light, and excellent in heat resistance, flexibility, and scratch resistance.

  In recent years, solar cells have received more attention as energy supply means in place of petroleum, which is an energy source that forms carbon dioxide, which causes global warming. The demand for solar cells is also increasing, and stable supply and cost reduction of various members constituting solar cell modules included in solar cells have been required. In addition, the demand for improving the power generation efficiency of solar cells has increased.

  In the solar cell module, a large number of plate-like solar cell elements are arranged, and these are wired in series and in parallel, and packaged to protect the elements and unitized. And this solar cell module usually uses a composition containing an ethylene / vinyl acetate copolymer having a high transparency and excellent moisture resistance by covering the surface of the solar cell element that is exposed to sunlight with a glass plate. Thus, the gap between the solar cell elements is filled to form a filler portion, and the back surface (the lower surface of the filler portion) is sealed with a solar cell back surface protective film.

  When a solar cell including a solar cell module is arranged on the roof of a house, it is preferred to be colored in a dark color such as black from the viewpoint of appearance. A solar cell back surface protective film colored in color has come to be used.

Examples of the film colored in a dark color include, for example, a sheet made of a low heat storage thermoplastic resin composition containing a thermoplastic resin and an inorganic pigment having infrared reflection characteristics (see Patent Document 1), a perylene pigment. There is known a sheet (see Patent Document 2) that has a black resin layer containing selenium on the surface and reflects near infrared rays by reflecting light with a wavelength of 800 to 1,100 nm with a reflectance of 30% or more. ing.
Also known is a laminate in which an infrared transmissive colored resin layer is arranged on one side of a thermoplastic resin layer having high heat resistance and a colored resin layer having high light reflectivity is arranged on the other side ( (See Patent Document 3).

JP 2007-103813 A JP 2007-128943 A JP 2009-119864 A

  The present invention provides a back surface protective film for solar cells and a solar cell module excellent in photoelectric conversion efficiency, heat resistance, flexibility and scratch resistance when sunlight is received on a surface having a dark color appearance. Objective.

  The present invention is shown below. In the following description, the hue symbol is also called a JIS symbol, but is based on the Munsell hue circle.

1. A layer (A layer) comprising an infrared transmitting colorant mixture comprising at least two kinds of colorants and a rubber-containing aromatic vinyl resin, titanium oxide having an average primary particle size of 0.24 μm or more, and a rubber-containing aromatic vinyl resin. A layer film comprising a layer (B layer), a layer containing a saturated polyester resin (C layer), and a layer containing a fluorine-based resin (D layer), the surface on the A layer side of the laminate film When a light having a wavelength of 740 nm is radiated to the solar cell, the solar cell back surface protective film has a reflectance of 20% or more.

2. The at least two colorants are selected from the group consisting of a red colorant and a green colorant, a purple colorant and a yellow colorant; and an orange colorant and a blue colorant. 2. The back surface protective film for solar cells according to 1 above, comprising at least one combination of colorants.

3. 2. The back protective film for solar cells according to 1 above, wherein the at least two colorants are at least four colorants.

4). 4. The solar cell back surface protective film according to 3 above, wherein the at least four colorants include a red colorant, a green colorant, a yellow colorant, and a purple colorant.

5). The back surface protective film for a solar cell according to any one of 1 to 4 above, wherein the fluorine-based resin is a polyvinylidene fluoride resin.

6). The back surface protection for solar cells according to any one of 1 to 5 above, wherein when the light having a wavelength of 400 to 700 nm is emitted to the surface on the A layer side of the back surface protective film for solar cells, the light absorption rate is 60% or more. the film.

7). When the light of wavelength 800-1400nm is radiated | emitted to the surface by the side of A layer in the back surface protective film for solar cells, the reflectance with respect to this light is for solar cells in any one of said 1 thru | or 6 which is 50% or more Back protection film.

8). The back surface protective film for solar cells according to any one of 1 to 7 above, comprising a water vapor barrier layer as an intermediate layer of the laminated film.

9. 9. The back surface protective film for solar cells according to 8 above, wherein the water vapor barrier layer is a vapor-deposited film having a film containing a metal and / or metal oxide formed on the surface thereof.

10. 10. The back surface protective film for solar cells according to any one of 1 to 9 above, wherein the thickness is 30 to 900 μm.

11. A solar cell module comprising the solar cell back surface protective film according to any one of 1 to 10 above.

  According to the back surface protective film for a solar cell of the present invention, when sunlight or the like is received on the surface on the A layer side, the dark color tone, particularly black appearance, is excellent, the photoelectric conversion efficiency is excellent, and heat deformation is suppressed and heat resistance is suppressed. Excellent in flexibility, flexibility and flame retardancy, good workability and handleability, and excellent adhesion to a member containing an ethylene / vinyl acetate copolymer. In addition, since the B layer is a white resin layer, when sunlight or the like enters from the A layer side, the light transmitted through the A layer can be reflected by the B layer, When a solar cell module is formed by adhering to a battery element and a filler part containing an ethylene / vinyl acetate copolymer that embeds the cell element and fills the gap, the photoelectric conversion efficiency can be improved by reflected light. it can.

  At least two colorants are selected from the group consisting of a red colorant and a green colorant, a purple colorant and a yellow colorant; and an orange colorant and a blue colorant In the case of including at least one combination of the colorants, a solar cell back surface protective film having excellent photoelectric conversion efficiency and having a dark color appearance can be obtained.

  When at least two kinds of colorants are at least four kinds of colorants, it is possible to obtain a back protective film for a solar cell with excellent photoelectric conversion efficiency and excellent dark appearance.

  When at least four colorants include a red colorant, a green colorant, a yellow colorant, and a purple colorant, the photoelectric conversion efficiency is excellent, and an extremely excellent dark appearance The solar cell back surface protective film can be obtained.

  When the fluororesin is a polyvinylidene fluoride resin, it is possible to obtain a back surface protective film for solar cells that is excellent in moldability and heat resistance and excellent in flame retardancy.

  When light having a wavelength of 400 to 700 nm is radiated on the surface of the A layer in the back surface protective film for solar cells, and the absorption rate for the light is 60% or more, the infrared transparent mixed coloring compounded in the A layer According to the color of the agent, it is possible to provide a solar cell module excellent in dark appearance, and when the solar cell module provided with the back surface protective film for solar cells is arranged on the roof of a house, the appearance is excellent. Designability etc. can be obtained.

  When light having a wavelength of 800 to 1,400 nm is radiated to the surface of the A layer in the back surface protective film for solar cells, when the reflectance with respect to the light is 50% or more, sunlight is adjacent to the solar cell element. When leaking from the gap to the back surface protective film, heat storage in the back surface protective film is suppressed. And reflected light can be made incident on a solar cell element, and power generation efficiency can be improved.

  When a water vapor barrier layer is provided as an intermediate layer of the laminated film, it can be a solar cell back surface protective film excellent in water vapor barrier properties from the surface on the A layer side and the surface on the C layer side.

  When the water vapor barrier layer is formed of a vapor deposition film having a film containing a metal and / or metal oxide formed on the surface thereof, a back surface protective film for solar cells having extremely excellent water vapor barrier properties can be obtained. it can.

  When the thickness of the back surface protective film for solar cells of the present invention is 30 to 900 μm, the flexibility is excellent.

  Since the solar cell module of the present invention comprises the solar cell back surface protective film of the present invention, it is suitable for outdoor use exposed to sunlight or wind and rain for a long period of time, and is excellent in power generation efficiency in the solar cell.

It is a schematic sectional drawing which shows an example of the back surface protective film for solar cells. It is a schematic sectional drawing which shows the other example of the back surface protective film for solar cells. It is a schematic sectional drawing which shows the other example of the back surface protective film for solar cells. It is a schematic sectional drawing which shows the other example of the back surface protective film for solar cells. It is a schematic sectional drawing which shows the other example of the back surface protective film for solar cells. It is a schematic sectional drawing which shows an example of a solar cell module.

  The present invention will be described in detail below. In this specification, “(co) polymerization” means homopolymerization and copolymerization. Further, “(meth) acryl” means acryl and methacryl, and “(meth) acrylate” means acrylate and methacrylate.

  The back surface protective film for solar cells of the present invention is a laminated film comprising an A layer, a B layer, a C layer, and a D layer in order, and its schematic cross section is illustrated in FIG. That is, the back surface protective film 1 for solar cells in FIG. 1 is a laminated film that includes the A layer 11, the B layer 12, the C layer 13, and the D layer 14 in order.

  Moreover, in the back surface protective film for solar cells of this invention, the outline in the case of providing a water vapor | steam barrier layer between A layer and B layer, between B layer and C layer, and / or between C layer and D layer. Cross sections are illustrated in FIGS. 2, 3 and 4. That is, the back surface protective film 1 for a solar cell in FIG. 2 is a laminated film provided with an A layer 11, a water vapor barrier layer 15, a B layer 12, a C layer 13 and a D layer 14 in this order. The back surface protective film 1 for a solar cell in FIG. 3 is a laminated film including an A layer 11, a B layer 12, a water vapor barrier layer 15, a C layer 13, and a D layer 14 in this order. The back surface protective film 1 for solar cells in FIG. 4 is a laminated film that includes an A layer 11, a B layer 12, a C layer 13, a water vapor barrier layer 14, and a D layer 14 in this order. Moreover, the back surface protective film 1 for solar cells of FIG. 5 is a laminated | multilayer film provided with the A layer 11, B layer 12, the water vapor | steam barrier layer 15a, the C layer 13, the water vapor | steam barrier layer 15b, and D layer 14 one by one.

<A layer>
The layer A is a dark resin layer containing an infrared transmitting colorant mixture composed of at least two kinds of colorants and a rubber-containing aromatic vinyl-based resin, and other resins or polymers (hereinafter referred to as described below) as necessary. , Both may be referred to as “other resins”) and additives. The infrared transparent mixed colorant is a mixture (mixed color) of two or more colorants having transparency in the infrared band and having a peak of the absorption spectrum in a part of the visible light band, and the absorption spectrum of each colorant. Is a colorant mixture in which the absorption spectrum extends over the entire visible light band. By mixing such a colorant mixture, a resin composition that has a dark visual appearance and transmits infrared rays can be obtained. Hereinafter, the composition which comprises A layer is demonstrated as a thermoplastic resin composition (I).

  First, the rubber-containing aromatic vinyl resin used for the A layer will be described.

  The rubber-containing aromatic vinyl resin is a rubber-reinforced aromatic vinyl resin obtained by polymerizing a vinyl monomer containing an aromatic vinyl compound and a vinyl cyanide compound in the presence of a rubbery polymer (hereinafter referred to as “rubber-reinforced aromatic vinyl resin”). A resin containing at least “resin (A1)”, and a copolymer (hereinafter referred to as “resin (A1)”, a structural unit derived from an aromatic vinyl compound and a structural unit derived from a vinyl cyanide compound (hereinafter “ Copolymer (A2) ”).

  The content of the rubbery polymer contained in the rubber-containing aromatic vinyl resin is usually 5 to 40% by mass, preferably 8 to 30% by mass, more preferably from the viewpoint of impact resistance and heat resistance in the molded product. It is 10-20 mass%, Most preferably, it is 12-18 mass%.

  The rubber-containing aromatic vinyl resin is composed of the resin (A1) or a combination of the resin (A1) and the copolymer (A2) as described above. Each of the resin (A1) and the copolymer (A2) may contain one kind or two or more kinds.

  Resin (A1) is a vinyl monomer (hereinafter “vinyl”) containing an aromatic vinyl compound and a vinyl cyanide compound in the presence of a rubber polymer (hereinafter referred to as “rubber polymer (a1-1)”). Is a rubber-reinforced aromatic vinyl resin obtained by polymerizing a monomer (a1-2) ”, and usually a vinyl monomer (a1-2) containing an aromatic vinyl compound is rubbery. By copolymer resin graft-copolymerized to polymer (a1-1) and ungrafted component not grafted to rubber polymer (a1-1), ie, remaining vinyl monomer (a1-2) (Co) polymers.

  The rubbery polymer (a1-1) used for forming the resin (A1) is not particularly limited as long as it is rubbery at room temperature, and may be either a homopolymer or a copolymer. Further, the rubbery polymer (a1-1) may be either a crosslinked polymer or a non-crosslinked polymer.

  The rubbery polymer (a1-1) is not particularly limited, but is conjugated diene rubber, hydrogenated conjugated diene rubber, ethylene / α-olefin copolymer rubber, acrylic rubber, silicone rubber, silicone / acrylic. A composite rubber etc. are mentioned. Two or more of these may be used. From the viewpoint of weather resistance, acrylic rubber, silicone rubber, silicone / acrylic composite rubber, ethylene / α-olefin copolymer rubber, hydrogenated conjugated diene rubber, and the like are preferable.

  The shape of the rubber-like polymer (a1-1) is not particularly limited, and may be particulate (spherical or substantially spherical), linear, curved, or the like. When it is in the form of particles, its volume average particle diameter is usually 5 to 2,000 nm, preferably 10 to 1,800 nm, and more preferably 50 to 1,500 nm. If the volume average particle diameter is in the above range, the processability and impact resistance of the thermoplastic resin composition (I) are excellent. The volume average particle diameter can be measured by image analysis using an electron micrograph, a laser diffraction method, a light scattering method, or the like.

  Examples of the conjugated diene rubber include polybutadiene, butadiene / styrene random copolymer, butadiene / styrene block copolymer, butadiene / acrylonitrile copolymer, and the like. Two or more of these may be used.

  In the present invention, the conjugated diene rubber preferably has a Tg of −20 ° C. or less from the viewpoints of flexibility, low temperature impact property and the like.

  As the acrylic rubber, a (co) polymer containing 80% by mass or more of structural units derived from an alkyl acrylate ester having an alkyl group having 2 to 8 carbon atoms based on the total amount of structural units constituting the acrylic rubber. Is preferred.

  Examples of the alkyl acrylate having 2 to 8 carbon atoms in the alkyl group include ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. Etc. Two or more of these may be used. Preferred alkyl acrylates are n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate.

  When the acrylic rubber contains structural units derived from other monomers, other monomers include monofunctional monofunctional monomers such as acrylonitrile, vinyl esters, methacrylic acid alkyl esters, (meth) acrylic acid, and styrene. Monomer or polyethylene glycol di (meth) acrylate such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, divinylbenzene, Examples thereof include crosslinkable monomers such as di- or triallyl compounds such as diallyl phthalate, diallyl maleate, diallyl succinate, triallyl triazine, and allyl compounds such as allyl (meth) acrylate.

  The acrylic rubber preferably has a Tg of −10 ° C. or less from the viewpoints of flexibility, low temperature impact property and the like. The acrylic rubber having Tg is usually a copolymer containing a structural unit derived from the crosslinkable monomer.

  The content of the structural unit derived from the crosslinkable monomer constituting the preferred acrylic rubber is usually 0.01 to 10% by mass, preferably 0.05 to 8% by mass, based on the total amount of the structural unit. More preferably, it is 0.1-5 mass%.

  The volume average particle diameter of the acrylic rubber is usually 5 to 500 nm, preferably 10 to 450 nm, and more preferably 20 to 400 nm from the viewpoints of flexibility, low temperature impact property and the like.

  The acrylic rubber is produced by a known method, but a preferred production method is an emulsion polymerization method.

  The silicone rubber is preferably a rubber contained in a latex in order to facilitate emulsion polymerization, which is a suitable method for producing a rubber-reinforced aromatic vinyl resin. Therefore, the silicone rubber is, for example, a polyorganosiloxane rubber produced by the method described in US Pat. Nos. 2,891,920, 3,294,725, etc. Can do.

  Polyorganosiloxane rubber is obtained by, for example, shear-mixing organosiloxane and water in the presence of a sulfonic acid-based emulsifier such as alkylbenzene sulfonic acid or alkyl sulfonic acid using a homomixer or an ultrasonic mixer, and then condensation. It is preferable that it is a silicone rubber contained in the latex obtained by this method. Alkylbenzenesulfonic acid is suitable because it acts as an emulsifier for organosiloxane and also as a polymerization initiator. In this case, it is preferable to use an alkylbenzene sulfonic acid metal salt, an alkyl sulfonic acid metal salt, or the like in combination because it has an effect of stably maintaining the silicone rubber when producing a rubber-reinforced aromatic vinyl resin.

  The polymer end of the polyorganosiloxane rubber may be sealed with, for example, a hydroxyl group, an alkoxy group, a trimethylsilyl group, a methyldiphenylsilyl group, or the like. Further, if necessary, a graft crossing agent and / or a crosslinking agent may be co-condensed within a range not impairing the target performance of the present invention. By using these, impact resistance can be improved.

The organosiloxane used in the above reaction is, for example, the general formula [R ¹ _m SiO _{(4-m) / 2} ] (wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group, and m is 0 to 0. 3 represents an integer of 3.). The structure of this compound is linear, branched or cyclic, but is preferably an organosiloxane having a cyclic structure. R ¹ possessed by the organosiloxane, that is, monovalent hydrocarbon groups include alkyl groups such as methyl group, ethyl group, propyl group and butyl group; aryl groups such as phenyl group and tolyl group; vinyl groups and allyl groups An alkenyl group such as: a group in which a part of hydrogen atoms bonded to carbon atoms in these hydrocarbon groups is substituted with a halogen atom, a cyano group, or the like; and at least one hydrogen atom in an alkyl group is substituted with a mercapto group Group and the like.

  Examples of organosiloxanes include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, etc. In addition to the cyclic compound, a linear or branched organosiloxane can be used. Two or more of these may be used.

  The organosiloxane may be a polyorganosiloxane condensed in advance, for example, having an Mw of about 500 to 10,000. When the organosiloxane is a polyorganosiloxane, the molecular chain terminal may be sealed with a hydroxyl group, an alkoxy group, a trimethylsilyl group, a methyldiphenylsilyl group, or the like.

  The graft crossing agent is usually a compound having a carbon-carbon unsaturated bond and an alkoxysilyl group. For example, p-vinylphenylmethyldimethoxysilane, 2- (p-vinylphenyl) ethylmethyldimethoxysilane, 3- ( p-Vinylbenzoyloxy) propylmethyldimethoxysilane and the like.

  The amount of the grafting agent used is usually 10 parts by mass or less, preferably 0.2 to 10 parts by mass, more preferably 0.5 to 100 parts by mass when the total of the organosiloxane, the grafting agent and the crosslinking agent is 100 parts by mass. 5 parts by mass. If the amount of the grafting agent used is too large, the molecular weight of the graft copolymer is lowered, and as a result, sufficient impact resistance may not be obtained.

  Examples of the crosslinking agent include trifunctional crosslinking agents such as methyltrimethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, and ethyltriethoxysilane, and tetrafunctional crosslinking agents such as tetraethoxysilane. In addition, you may use the crosslinkable prepolymer which prepolymerizes these compounds. Two or more of these may be used.

  The amount of the crosslinking agent used is usually 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 0.01 to 5 parts by mass, when the total of the organosiloxane, the grafting agent and the crosslinking agent is 100 parts by mass. is there. When there is too much usage-amount of a crosslinking agent, the softness | flexibility of the polyorganosiloxane type rubber | gum obtained will be impaired and the flexibility of a film may fall.

  The volume average particle diameter of the silicone rubber is usually 5 to 500 nm, preferably 10 to 400 nm, and more preferably 50 to 400 nm. This volume average particle diameter can be easily controlled by the amount of emulsifier and water used during production, the degree of dispersion when mixed using a homomixer or an ultrasonic mixer, or the method of charging the organosiloxane. If the volume average particle diameter exceeds 500 nm, the appearance may be inferior, such as a decrease in gloss.

  Silicone / acrylic composite rubber is a rubbery polymer containing polyorganosiloxane rubber and polyalkyl (meth) acrylate rubber. A preferable silicone-acrylic composite rubber is a composite rubber having a structure in which polyorganosiloxane rubber and polyalkyl (meth) acrylate rubber are intertwined with each other so that they cannot be separated.

  As the polyorganosiloxane-based rubber, a copolymer obtained by copolymerizing an organosiloxane can be preferably used. Examples of the organosiloxane include various reductants having three or more members, such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetra Methyl tetraphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxane and the like are preferable. And these organosiloxanes may use 2 or more types.

  The content of the structural unit derived from the organosiloxane constituting the polyorganosiloxane rubber is usually 50% by mass or more, preferably 70% by mass or more based on the total amount of the structural unit.

  The polyalkyl (meth) acrylate rubber is preferably methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, ethoxyethoxyethyl acrylate, methoxytripropylene glycol acrylate, 4-hydroxybutyl. It is a rubber obtained by (co) polymerizing a monomer containing a (meth) acrylic acid alkyl ester compound such as acrylate, lauryl methacrylate, stearyl methacrylate and the like. Two or more of these (meth) acrylic acid alkyl ester compounds may be used.

  In addition to the (meth) acrylic acid alkyl ester compounds, the monomers include aromatic vinyl compounds such as styrene, α-methylstyrene, and vinyl toluene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; methacrylic acid Various vinyl monomers such as modified silicone and fluorine-containing vinyl compound may be contained in the range of 30% by mass or less.

  The polyalkyl (meth) acrylate rubber is preferably a copolymer having two or more Tg since it can impart sufficient flexibility to the film.

  As the silicone / acrylic composite rubber, for example, those manufactured by the methods described in JP-A-4-239010, JP-A-4-100812 and the like can be used.

  The volume average particle diameter of the silicone / acrylic composite rubber is usually 5 to 500 nm, preferably 10 to 450 nm, and more preferably 20 to 400 nm from the viewpoints of flexibility, low temperature impact property and the like.

  The ethylene / α-olefin copolymer rubber is a copolymer including an ethylene unit and a structural unit composed of an α-olefin having 3 or more carbon atoms, and includes an ethylene / α-olefin copolymer, ethylene / α- Examples include olefin / non-conjugated diene copolymers.

  Examples of the ethylene / α-olefin copolymer include an ethylene / propylene copolymer and an ethylene / butene-1 copolymer. Examples of the ethylene / α-olefin / non-conjugated diene copolymer include an ethylene / propylene / non-conjugated diene copolymer and an ethylene / butene-1 / non-conjugated diene copolymer.

  The hydrogenated conjugated diene rubber is not particularly limited as long as it is a (co) polymer obtained by hydrogenating a (co) polymer containing a structural unit derived from a conjugated diene compound.

  Examples of the hydrogenated conjugated diene rubber include a hydrogenated product of a conjugated diene block copolymer. That is, a polymer block A comprising a structural unit derived from an aromatic vinyl compound; a double bond portion of a polymer comprising a structural unit derived from a conjugated diene compound having a 1,2-vinyl bond content exceeding 25 mol%. Polymer block B formed by hydrogenation of 95 mol% or more; 95 mol% or more of a double bond portion of a polymer composed of a structural unit derived from a conjugated diene compound having a 1,2-vinyl bond content of 25 mol% or less Hydrogenated polymer block C formed by hydrogenation; and 95 mol% or more of a double bond portion of a copolymer composed of a structural unit derived from an aromatic vinyl compound and a structural unit derived from a conjugated diene compound. Is a block copolymer composed of a combination of two or more of polymer blocks D.

  Hydrogenated conjugated diene rubbers include hydrogenated polybutadiene, hydrogenated styrene / butadiene rubber, styrene / ethylene butylene / olefin crystal block polymer, olefin crystal / ethylene butylene / olefin crystal block polymer, styrene / ethylene butylene / styrene block polymer, Examples thereof include a hydrogenated product of a butadiene / acrylonitrile copolymer.

  The vinyl monomer (a1-2) used for forming the resin (A1) contains an aromatic vinyl compound and a vinyl cyanide compound. That is, the vinyl monomer (a1-2) may be composed of only an aromatic vinyl compound and a vinyl cyanide compound, an aromatic vinyl compound and a vinyl cyanide compound, and these compounds. It may be composed of other monomers copolymerizable with. Other monomers include (meth) acrylic acid ester compounds, maleimide compounds, unsaturated acid anhydrides, carboxyl group-containing unsaturated compounds, hydroxyl group-containing unsaturated compounds, epoxy group-containing unsaturated compounds, oxazoline group-containing And unsaturated compounds. Two or more of these may be used.

  The aromatic vinyl compound is not particularly limited as long as it is a compound having at least one vinyl bond and at least one aromatic ring. Examples thereof include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, β-methylstyrene, ethylstyrene, p-tert-butylstyrene, vinyltoluene, vinylxylene, vinylnaphthalene, monochlorostyrene, dichloromethane. Examples thereof include styrene, monobromostyrene, dibromostyrene, tribromostyrene, and fluorostyrene. Two or more of these compounds may be used. Of these, styrene and α-methylstyrene are preferable, and styrene is particularly preferable.

  Examples of the vinyl cyanide compound include acrylonitrile, methacrylonitrile, ethacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile and the like. Two or more of these compounds may be used. Of these, acrylonitrile is preferred.

  Examples of the (meth) acrylate compound include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, ( (Meth) acrylic acid isobutyl, (meth) acrylic acid sec-butyl, (meth) acrylic acid tert-butyl, (meth) acrylic acid hexyl, (meth) acrylic acid n-octyl, (meth) acrylic acid 2-ethylhexyl, ( Examples thereof include cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, and the like. Two or more of these compounds may be used.

  As maleimide compounds, maleimide, N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-dodecylmaleimide, N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (4-methylphenyl) ) Maleimide, N- (2,6-dimethylphenyl) maleimide, N- (2,6-diethylphenyl) maleimide, N- (2-methoxyphenyl) maleimide, N-benzylmaleimide, N- (4-hydroxyphenyl) Maleimide, N-naphthylmaleimide, N-cyclohexylmaleimide and the like can be mentioned. Of these, N-phenylmaleimide is preferred. Two or more of these compounds may be used. In addition, as another method of introducing the structural unit derived from the maleimide compound into the resin (A1), for example, a method of copolymerizing an unsaturated dicarboxylic anhydride of maleic anhydride and then imidizing may be used.

  Examples of the unsaturated acid anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride and the like. Two or more of these compounds may be used.

  Examples of the carboxyl group-containing unsaturated compound include (meth) acrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, cinnamic acid and the like. Two or more of these compounds may be used.

  Examples of the hydroxyl group-containing unsaturated compound include (meth) acrylic acid ester having a hydroxyl group such as 2-hydroxymethyl (meth) acrylate; o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene and the like. Two or more of these compounds may be used.

  Examples of the epoxy group-containing unsaturated compound include glycidyl (meth) acrylate, 3,4-oxycyclohexyl (meth) acrylate, vinyl glycidyl ether, allyl glycidyl ether, and methallyl glycidyl ether. Two or more of these compounds may be used.

  Examples of the oxazoline group-containing unsaturated compound include vinyl oxazoline.

  In the present invention, the total content of the aromatic vinyl compound and the vinyl cyanide compound contained in the vinyl monomer (a1-2) is moldability, chemical resistance, hydrolysis resistance, dimensional stability, From the viewpoint of molding appearance and the like, it is usually 70 to 100% by mass, preferably 80 to 100% by mass, based on the total amount of the vinyl monomer (a1-2). The use ratio of the aromatic vinyl compound and the vinyl cyanide compound was 100% by mass in total from the viewpoint of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, and the like. In this case, it is usually 5 to 95% by mass and 5 to 95% by mass, preferably 50 to 95% by mass and 5 to 50% by mass, and more preferably 60 to 95% by mass and 5 to 40% by mass, respectively.

  As the resin (A1), preferred resins are as follows.

  [1-1]: Rubber reinforcement obtained by polymerizing a vinyl monomer (a1-2) composed of an aromatic vinyl compound and a vinyl cyanide compound in the presence of a rubbery polymer (a1-1). Aromatic vinyl resin.

  [1-2]: Obtained by polymerizing a vinyl monomer (a1-2) composed of an aromatic vinyl compound, a vinyl cyanide compound and a maleimide compound in the presence of the rubbery polymer (a1-1). Rubber-reinforced aromatic vinyl resin.

  [1-3]: In the presence of the rubbery polymer (a1-1), a vinyl monomer (a1-2) composed of an aromatic vinyl compound, a vinyl cyanide compound and a methacrylic ester compound is polymerized. The resulting rubber-reinforced aromatic vinyl resin.

  The resin (A1) can be produced by polymerizing the vinyl monomer (a1-2) in the presence of the rubbery polymer (a1-1). As a polymerization method, emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, or a combination of these can be used.

  In the production of the resin (A1), the rubber polymer (a1-1) and the vinyl monomer (a1-2) are used in the reaction system in the total amount of the rubber polymer (a1-1). In the presence, the vinyl monomer (a1-2) may be added all at once to initiate the polymerization, or the polymerization may be carried out separately or continuously. In addition, in the presence or absence of a part of the rubbery polymer (a1-1), the vinyl monomer (a1-2) may be added all at once to initiate polymerization, or may be divided. Or may be added continuously. At this time, the remainder of the rubber-like polymer (a1-1) may be added all at once during the reaction, divided or continuously.

  When the resin (A1) is produced by emulsion polymerization, a polymerization initiator, a chain transfer agent (molecular weight regulator), an emulsifier, water and the like are used.

  Examples of the polymerization initiator include a redox initiator in which a known organic peroxide and a reducing agent such as a sugar-containing pyrophosphate formulation and a sulfoxylate formulation are combined; a known persulfate; a known peroxide, and the like. Can be mentioned. You may use these in combination of 2 or more type. Moreover, the usage-amount of a polymerization initiator is 0.1-1.5 mass% normally with respect to vinyl-type monomer (a1-2) whole quantity. The polymerization initiator can be added to the reaction system all at once or continuously.

  Examples of the chain transfer agent include mercaptans; terpinolenes, α-methylstyrene dimers, and the like. You may use these in combination of 2 or more type. The usage-amount of a chain transfer agent is 0.05-2.0 mass% normally with respect to vinyl-type monomer (a1-2) whole quantity. The chain transfer agent can be added to the reaction system all at once or continuously.

  Examples of the emulsifier include anionic surfactants and nonionic surfactants. Examples of the anionic surfactant include higher alcohol sulfates; alkylbenzene sulfonates; aliphatic sulfonates; higher aliphatic carboxylates; aliphatic phosphates. Examples of nonionic surfactants include polyethylene glycol alkyl ester compounds and alkyl ether compounds. You may use these in combination of 2 or more type. The usage-amount of an emulsifier is 0.3-5.0 mass% normally with respect to vinyl-type monomer (a1-2) whole quantity.

  Emulsion polymerization can be performed on well-known conditions according to kinds, such as a vinyl-type monomer (a1-2) and a polymerization initiator. The latex obtained by this emulsion polymerization is usually coagulated with a coagulant to make the resin component powdery, and then washed with water and dried to obtain a purified resin. Examples of the coagulant include inorganic salts such as calcium chloride, magnesium sulfate, magnesium chloride, and sodium chloride; inorganic acids such as sulfuric acid and hydrochloric acid; organic acids such as acetic acid and lactic acid.

  When two or more kinds of resins (A1) are contained in the thermoplastic resin composition (I), a resin coagulated from one latex (A1-a) and a resin coagulated from another latex (A1- The method of mixing with b) The method of coagulating after preparing the mixture which consists of 1 latex and another latex, etc. can be applied.

  A known method can be applied to the method for producing the resin (A1) by solution polymerization, bulk polymerization, and bulk-suspension polymerization.

  In addition, as resin (A1), the commercial item which has structures, such as a silicone rubber reinforcement | strengthening aromatic vinyl-type resin and a silicone acrylic resin reinforcement | strengthening aromatic vinyl-type resin, can be used. For example, as the resin (A1) using a silicone / acrylic composite rubber as the rubber polymer (a1-1), for example, Mitsubishi Rayon, which is a commercial product obtained by the method described in JP-A-4-239010, can be used. “Metablene SX-006” (trade name) manufactured by the company, and the like.

  The graft ratio of the resin (A1) is usually 20 to 170%, preferably 30 to 170%, more preferably 40 to 150%. If this graft ratio is too low, flexibility may not be sufficient. On the other hand, when the graft ratio is too high, the viscosity of the resin (A1) tends to increase, and it may be difficult to reduce the thickness of the thermoplastic resin composition (I).

The graft ratio can be determined by the following formula.
[Equation 1]
Graft rate (%) = {(S−T) / T} × 100

  In the above formula, 1 g of resin (A1) is added to 20 ml of acetone and shaken with a shaker for 2 hours under a temperature condition of 25 ° C. Then, a centrifuge ( Rotational speed: 23,000 rpm) for 60 minutes, the mass (g) of the insoluble matter obtained by separating the insoluble matter and the soluble matter, and T is a rubbery substance contained in 1 gram of the resin (A1) It is the mass (g) of the polymer (a1-1). The mass of the rubbery polymer (a1-1) can be obtained by a method of calculating from a polymerization prescription and a polymerization conversion rate, a method of obtaining from an infrared absorption spectrum (IR), and the like.

  The graft ratio is easily controlled by adjusting the type and amount of the polymerization initiator, chain transfer agent, emulsifier, solvent, etc. used in producing the resin (A1), and further the polymerization time, polymerization temperature, etc. be able to.

  Two or more types of resins (A1) may be used.

  The copolymer (A2) constituting the rubber-containing aromatic vinyl resin together with the resin (A1) includes a structural unit derived from an aromatic vinyl compound (hereinafter referred to as “structural unit (sa-1)”) and a vinyl cyanide compound. Is a copolymer containing a structural unit derived from (hereinafter referred to as “structural unit (sa-2)”).

  The copolymer (A2) may be composed only of the structural units (sa-1) and (sa-2), the structural units (sa-1) and (sa-2), and a fragrance. It may be composed of a structural unit derived from another monomer copolymerizable with a group vinyl compound and a vinyl cyanide compound (hereinafter referred to as “structural unit (sa-3)”). Other monomers include (meth) acrylic acid ester compounds, maleimide compounds, unsaturated acid anhydrides, carboxyl group-containing unsaturated compounds, hydroxyl group-containing unsaturated compounds, epoxy group-containing unsaturated compounds, oxazoline group-containing And unsaturated compounds. The compound illustrated in the vinyl-type monomer (a1-2) is applied to each said compound. The structural unit (sa-3) may be a structural unit derived from one type of monomer, or may be two or more types of structural units derived from two or more types of monomers. Moreover, as the structural unit (sa-3), a structural unit derived from a maleimide compound is preferable.

  The total content of the structural units (sa-1) and (sa-2) contained in the copolymer (A2) is the sum of the structural units (sa-1), (sa-2) and (sa-3). When it is 100 mass%, it is 40-100 mass% normally, Preferably it is 50-100 mass%. In addition, the content ratio of the structural units (sa-1) and (sa-2) is 100 in total from the viewpoint of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, and the like. In the case of mass%, it is usually 5 to 95 mass% and 5 to 95 mass%, preferably 40 to 95 mass% and 5 to 60 mass%, more preferably 50 to 90 mass% and 10 to 50 mass%.

  When the copolymer (A2) includes a structural unit (sa-3), and this structural unit (sa-3) is a structural unit derived from a maleimide compound, heat resistance can be imparted. .

  As the copolymer (A2), preferred polymers are as follows.

  [1-5]: A copolymer comprising structural units (sa-1) and (sa-2).

  [1-6]: A copolymer comprising structural units (sa-1) and (sa-2) and a structural unit derived from a maleimide compound (hereinafter referred to as “structural unit (sa-3m)”).

  When the copolymer (A2) is in the mode [1-5], the content ratios of the structural units (sa-1) and (sa-2) are molding processability, chemical resistance, hydrolysis resistance, and dimensional stability. From the viewpoints of properties, molding appearance, etc., when these totals are 100% by mass, usually 5 to 95% by mass and 5 to 95% by mass, preferably 40 to 95% by mass and 5 to 60% by mass, respectively. More preferably, they are 50-90 mass% and 10-50 mass%.

  Examples of the copolymer of the embodiment [1-5] include a styrene / acrylonitrile copolymer, an α-methylstyrene / acrylonitrile copolymer, and a styrene / α-methylstyrene / acrylonitrile copolymer.

  When the copolymer (A2) is the embodiment [1-6], the content ratio of the structural units (sa-1), (sa-2) and (sa-3m) is determined by molding processability, heat resistance and chemical resistance. From the viewpoints of properties, hydrolysis resistance, dimensional stability, flexibility, etc., when these are 100% by mass, usually 10 to 90% by mass, 9.5 to 70% by mass, and 0.5%, respectively. -30 mass%, preferably 20-85 mass%, 14-60 mass% and 1-20 mass%, more preferably 30-80 mass%, 18-50 mass% and 2-15 mass%.

  Examples of the copolymer of the embodiment [1-6] include a styrene / acrylonitrile / N-phenylmaleimide copolymer.

  As the copolymer (A2), a styrene / acrylonitrile / methyl methacrylate copolymer or the like may be used.

  The copolymer (A2) is a vinyl monomer containing an aromatic vinyl compound and a vinyl cyanide compound in the presence or absence of a polymerization initiator (hereinafter referred to as “vinyl monomer (a2)”). Can be produced by polymerization. When a polymerization initiator is used as the polymerization method, solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization and the like are suitable, and these polymerization methods may be used in combination. Moreover, when not using a polymerization initiator, it can be set as thermal polymerization.

  As a polymerization initiator, the compound illustrated by description of the manufacturing method of resin (A1) can be used. The usage-amount of a polymerization initiator is 0.1-1.5 mass% normally with respect to vinyl-type monomer (a2) whole quantity.

  Depending on the polymerization method, chain transfer agents, emulsifiers and the like that can be used at the time of producing the resin (A1) can be used.

  In the production of the copolymer (A2), the polymerization may be started in a state where the entire amount of the vinyl monomer (a2) is accommodated in the reaction system, or the arbitrarily selected monomer component is divided. You may superpose | polymerize by adding or adding continuously. Further, when a polymerization initiator is used, it can be added to the reaction system all at once or continuously.

  Two or more types of copolymers (A2) may be used.

  The intrinsic viscosity [η] (measured in methyl ethyl ketone at 30 ° C.) of the acetone-soluble component of the rubber-containing aromatic vinyl resin is usually 0.1 to 2.5 dl / g, preferably 0.2 to 1. 5 dl / g, more preferably 0.25 to 1.2 dl / g. When the intrinsic viscosity [η] is within the above range, the thermoplastic resin composition (I) is excellent in molding processability and also in thickness accuracy.

  Here, the intrinsic viscosity [η] can be obtained in the following manner. That is, when determining the graft ratio in the resin (A1), acetone-soluble components recovered after centrifugation are dissolved in methyl ethyl ketone, and five different concentrations are prepared. Using an Ubbelohde viscosity tube at 30 ° C. The intrinsic viscosity [η] is determined by measuring the reduced viscosity at each concentration.

  Intrinsic viscosity [η] is the type and amount of polymerization initiator, chain transfer agent, emulsifier, solvent, etc. used when producing the resin (A1) and copolymer (A2), and further the polymerization time, polymerization temperature, etc. It can be easily controlled by adjusting.

  The intrinsic viscosity [η] can also be adjusted by appropriately selecting a resin (A1) and a copolymer (A2) having different intrinsic viscosities [η].

  As described above, the thermoplastic resin composition (I) may be composed of only a rubber-containing aromatic vinyl resin, or may be composed of a rubber-containing aromatic vinyl resin and another resin. There may be.

  Other resins include acrylic resins containing structural units derived from (meth) acrylic acid ester compounds; saturated polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate; polyolefin resins; polyvinyl chloride resins; polyvinylidene chloride Resin; Polyvinyl acetate resin; Polycarbonate resin; Fluororesin; Ethylene / vinyl acetate resin and the like. Two or more of these may be used.

  When the thermoplastic resin composition (I) contains another resin, the content thereof is usually less than 50% by mass, preferably 40% by mass or less, more preferably 30%, based on the rubber-containing aromatic vinyl resin. It is below mass%. When said content rate is too high, the effect using resin (A1) based on this invention will become small.

  The content ratio of the resin (A1) and the copolymer (A2) in the thermoplastic resin composition (I) and other resins used in combination as necessary is the rubber weight derived from the resin (A1). The content of the coalescence (a1-1) is usually adjusted to 5 to 40% by mass, preferably 8 to 30% by mass, more preferably 10 to 20% by mass, and particularly preferably 12 to 18% by mass. . When the content of the rubbery polymer (a1-1) contained in the thermoplastic resin composition (I) exceeds 40% by mass, the heat resistance may not be sufficient. On the other hand, when the content is less than 5% by mass, the impact resistance may not be sufficient.

  The thermoplastic resin composition (I) contains an infrared transmitting colorant mixture composed of at least two kinds of colorants. The explanation of the infrared transmitting colorant mixture will be described later.

  The thermoplastic resin composition (I) can contain an additive depending on the purpose and application. This additive includes antioxidants, ultraviolet absorbers, anti-aging agents, plasticizers, fluorescent brighteners, weathering agents, fillers, antistatic agents, flame retardants, antifogging agents, antibacterial agents, antifungal agents, Antifouling agents, tackifiers, silane coupling agents and the like can be mentioned. Specific compounds in these additives and their contents will be described later.

  The thickness of the A layer is usually 10 to 300 μm, preferably 15 to 250 μm, more preferably 20 to 200 μm, from the viewpoint of the strength and flexibility of the back protective film for solar cells of the present invention.

<B layer>
The B layer is a white resin layer containing titanium oxide having an average primary particle size of 0.24 μm or more and a rubber-containing aromatic vinyl resin, and mainly reflects infrared and visible light transmitted through the B layer. It is a layer which has the effect | action which maintains the balance of flexibility which the back surface protective film for solar cells has.

  The rubber-containing aromatic vinyl resin contained in the B layer is the same as the rubber-containing aromatic vinyl resin (resin (A1) or a combination of the resin (A1) and the copolymer (A2)) contained in the A layer. Or may be different, and the description (configuration and manufacturing method) is applied. Moreover, you may contain other resin, an additive, etc. similar to A layer as needed. Hereinafter, the composition which comprises B layer is demonstrated as a thermoplastic resin composition (II).

  Preferred resins (A1) included in the B layer are as follows.

  [2-1]: Rubber reinforcement obtained by polymerizing a vinyl monomer (a1-2) comprising an aromatic vinyl compound and a vinyl cyanide compound in the presence of the rubbery polymer (a1-1). Aromatic vinyl resin.

  [2-2]: Obtained by polymerizing a vinyl monomer (a1-2) comprising an aromatic vinyl compound, a vinyl cyanide compound and a maleimide compound in the presence of the rubbery polymer (a1-1). Rubber-reinforced aromatic vinyl resin.

  [2-3]: In the presence of the rubbery polymer (a1-1), a vinyl monomer (a1-2) composed of an aromatic vinyl compound, a vinyl cyanide compound and a methacrylic ester compound is polymerized. The resulting rubber-reinforced aromatic vinyl resin.

  In the above aspect, the description of [1-1] to [1-3] in the A layer is applied to a preferable configuration.

  Two or more types of resins (A1) may be used.

  Moreover, a preferable copolymer (A2) is as follows.

  [2-5]: A copolymer composed of structural units (sa-1) and (sa-2).

  [2-6]: A copolymer composed of structural units (sa-1), (sa-2), and (sa-3m).

  In the above embodiment, the description of [1-5] and [1-6] in the A layer is applied to a preferable configuration. In particular, in the embodiment [2-6], when the content of the structural unit (sa-3m) is 2 to 15% by mass, the durability in the cooling and heating cycle can be improved.

  Two or more types of copolymers (A2) may be used.

  When the thermoplastic resin composition (II) contains other resins, the content thereof is usually less than 50% by mass, preferably 40% by mass or less, more preferably relative to the rubber-containing aromatic vinyl resin. 30% by mass or less. When said content rate is too high, the effect using resin (A1) based on this invention will become small.

  The thermoplastic resin composition (II) contains titanium oxide having an average primary particle size of 0.24 μm or more. As the titanium oxide, titanium oxides such as anatase form and rutile form can be used as the crystal form, but the rutile form is preferred. The average primary particle diameter of titanium oxide is usually 0.25 μm or more, preferably 0.26 μm or more. The average primary particle diameter of titanium oxide can be measured by an image analyzer based on, for example, a transmission electron micrograph. The upper limit of the average primary particle diameter of titanium oxide is usually about 0.5 μm, preferably about 0.4 μm. Examples of titanium oxide having an average primary particle size of 0.24 μm or more include commercially available products such as “Taipaque CR-95” (average primary particle size of 0.28 μm), “Taipaque CR-58-2”. (Average primary particle diameter 0.28 μm), “Taipeku CR-50-2” (average primary particle diameter 0.25 μm), and the like.

  The content of titanium oxide having an average primary particle size of 0.24 μm or more is usually 1 to 45% by mass with respect to the rubber-containing aromatic vinyl resin, preferably from the viewpoint of reflectivity with respect to light having a wavelength of 700 to 1,400 nm. Is 3 to 40% by mass, more preferably 5 to 30% by mass. If the content of titanium oxide having an average primary particle size of 0.24 μm or more is too large, the flexibility of the back surface protective film for solar cell of the present invention may be lowered.

  The B layer is a white resin layer, and the L value (brightness) on the surface of the film composed of the single layer is usually 60 or more, preferably 65 or more, more preferably 70 or more.

  As long as the thermoplastic resin composition (II) does not decrease the L value, other colorants other than white colorants such as titanium oxide (for example, yellow colorants, blue colorants, etc.) May be included. When using other colorants, the content thereof is usually 10% by mass or less based on the thermoplastic resin composition (II).

  When the thermoplastic resin composition (II) contains an additive, its specific compound and content will be described later.

  The thickness of B layer is 10-300 micrometers normally, Preferably it is 15-250 micrometers, More preferably, it is 20-200 micrometers. When the thickness is in the above range, the balance of flexibility in the back surface protective film for solar cell of the present invention can be maintained at a high level.

<C layer>
The C layer is a resin layer containing a saturated polyester resin. This C layer is a layer mainly imparting durability to the back surface protective film for solar cell of the present invention. That is, in the solar cell back surface protective film of the present invention having the C layer having such properties, thermal deformation due to the use of the solar cell is suppressed, and heat resistance is excellent. When the C layer contains a white colorant, the light transmitted through the A layer and the B layer can be reflected to the A layer side.

  The saturated polyester resin contained in the C layer may be the same as or different from the thermoplastic resin in the A layer, and the description (configuration and manufacturing method) is applied. Moreover, you may contain the same additive in another resin or polymer, a coloring agent, A layer, and B layer as needed. From the viewpoint of strength and dimensional stability, a polyethylene terephthalate resin is preferably used. Hereinafter, the composition constituting the C layer will be described as the thermoplastic resin composition (III).

  Other resins include acrylic resins containing structural units derived from (meth) acrylic acid ester compounds; aromatic vinyl resins containing structural units derived from aromatic vinyl compounds; polyolefin resins; polyvinyl chloride resins; Examples thereof include vinylidene resin; polyvinyl acetate resin; polycarbonate resin; fluororesin; ethylene / vinyl acetate resin. Two or more of these may be used.

  When the thermoplastic resin composition (III) contains other resins, the content thereof is usually less than 50% by mass, preferably 40% by mass or less, more preferably 30% by mass or less, based on the saturated polyester resin. is there. When said content rate is too high, the physical property of C layer may become impossible to maintain, and it exists in the tendency for the effect of saturated polyester resin to fall.

  The C layer may be a colored resin layer or an uncolored resin layer. Therefore, the thermoplastic resin composition (III) may or may not contain a colorant.

  When the C layer has light reflectivity, sunlight leaks from the gap between adjacent solar cell elements toward the solar cell back surface protective film (A layer side) and passes through the A layer and the B layer. The reflected light can be reflected from the C layer, and the reflected light can be incident on the solar cell element to improve the power generation efficiency.

When it is set as C layer which has light reflectivity, it is preferable that thermoplastic resin composition (III) contains a white colorant. Examples of the white colorant include titanium oxide, zinc oxide, calcium carbonate, barium sulfate, calcium sulfate, alumina, silica, 2PbCO ₃ .Pb (OH) ₂ , [ZnS + BaSO ₄ ], talc, and gypsum. Two or more of these may be used.

  The content of the white colorant is usually from 1 to 45% by mass, preferably from 3 to 40% by mass, more preferably from the viewpoint of reflectivity for light having a wavelength of from 800 to 1,400 nm, which will be described later. Is 5-30 mass%. When there is too much content of a white type coloring agent, the flexibility of the back surface protection film for solar cells of this invention may fall.

  The thermoplastic resin composition (III) may contain a colorant other than the white colorant (for example, a yellow colorant, a blue colorant, etc.). When using other colorants, the content thereof is usually 10% by mass or less based on the thermoplastic resin composition (III).

  When the thermoplastic resin composition (III) contains an additive, its specific compound and content will be described later.

  In addition, a commercially available saturated polyester resin film can also be used for C layer. Commercially available products include, for example, “Lumirror E20” (trade name) manufactured by Toray, “PET film U2” (trade name) manufactured by Teijin DuPont Films, “Lumirror X10P” (trade name), “Lumirror X10S” manufactured by Toray. (Trade name), "Melinex 238" (trade name) manufactured by Teijin DuPont Films, "Teijin Tetron Film VW" (trade name) manufactured by Teijin DuPont Films, "SR55" (trade name) manufactured by SKC, etc. can be used. .

  When a film having flame retardancy is used as a film containing a saturated polyester resin, the fire resistance from the C layer side surface of the back surface protective film for solar cells can be increased, which is preferable. In addition, it is preferable that the flame retardance of the film which has a flame retardance is a UL94VTM-2 class or more class.

  The thickness of C layer is 10-300 micrometers normally, Preferably it is 15-250 micrometers, More preferably, it is 20-200 micrometers. When the thickness is too thin, the protective effect on the C-layer side surface of the solar cell back surface protective film of the present invention is insufficient, and when it is too thick, the flexibility of the solar cell back surface protective film is insufficient. .

<D layer>
The D layer is a resin layer containing a fluorine resin. This D layer is a layer mainly imparting heat resistance and flame retardancy to the solar cell back surface protective film of the present invention. That is, in the back surface protection film for solar cells of the present invention having the D layer having such properties, thermal deformation due to the use of the solar cells is suppressed, and the heat resistance is excellent and the flame retardancy is also excellent. When this D layer contains a white colorant, the light transmitted through the A layer, the B layer, and the C layer can be reflected to the A layer side.

  The composition which comprises D layer is demonstrated as a thermoplastic resin composition (IV). That is, this thermoplastic resin composition (IV) is a composition containing a fluororesin, and if necessary, in other resins or polymers, colorants, A layer, B layer or C layer. You may contain the same additive etc.

  The thermoplastic resin composition (IV) contains a fluororesin, and may contain other resins or polymers as necessary. Fluorocarbon resins include ETFE (ethylene / tetrafluoroethylene copolymer), PCTEFE (ethylene trifluoride chloroethylene resin), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoride). Ethylene-hexafluoropropylene copolymer), PVDF (vinylidene fluoride resin), PVF (vinyl fluoride resin), and the like. From the viewpoint of adhesiveness and moldability, PVDF is preferably used.

The PVDF resin may be a vinylidene fluoride homopolymer, a copolymer containing 70 mol% or more of vinylidene fluoride as a structural unit, and a mixture of these polymers. Examples of the monomer copolymerized with vinylidene fluoride include ethylene tetrafluoride, propylene hexafluoride, ethylene trifluoride, ethylene trifluoride chloride, vinyl fluoride, and the like. Can be used. The melting point of the PVDF resin is in the range of 146 to 178 ° C., but is preferably 165 ° C. or higher, more preferably 170 ° C. or higher, from the viewpoint of film adhesiveness and film appearance.

In addition, for the purpose of enhancing the adhesiveness with other resin layers, other resins than the fluorine-based resin can be mixed. Examples of other resins include acrylic resins. Copolymer containing MMA (methyl methacrylate) homopolymer as an acrylic resin, MMA monomer as a structural unit and 50 mol% or more and acrylic acid ester or methacrylic acid ester other than MMA less than 50 mol%. Examples thereof include a combination, and a mixture of two or more of these polymers.

Examples of the acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate (BA). Examples of the methacrylic ester other than MMA include ethyl methacrylate and propyl methacrylate. The copolymer is not limited to a random copolymer, and for example, a graft copolymer may be used. Examples of the mixed resin containing a fluororesin as a main component and other resin added include a mixed resin of 50 to 95% by mass of PVDF and 5 to 50% by mass of the acrylic resin.

    When the thermoplastic resin composition (IV) contains another resin, the content thereof is preferably less than 50% by mass, more preferably 40% by mass or less, still more preferably 30% by mass with respect to the fluororesin. It is as follows. If the content is too high, the physical properties of the D layer may not be maintained, and the effect of using the fluororesin tends to decrease.

  The D layer may be a colored resin layer or an uncolored resin layer. Therefore, the thermoplastic resin composition (IV) may or may not contain a colorant.

  When the D layer has light reflectivity, sunlight leaks from the gap between the adjacent solar cell elements toward the solar cell back surface protective film (A layer side), and the A layer, the B layer, and the C layer. The light transmitted through the layer can be reflected from the D layer, and the reflected light can be incident on the solar cell element to improve the power generation efficiency.

When the D layer having light reflectivity is used, the thermoplastic resin composition (IV) preferably contains a white colorant. Examples of the white colorant include titanium oxide, zinc oxide, calcium carbonate, barium sulfate, calcium sulfate, alumina, silica, 2PbCO ₃ .Pb (OH) ₂ , [ZnS + BaSO ₄ ], talc, and gypsum. These may be used alone or in combination of two or more.

  The content of the white colorant is preferably 1 to 45% by mass, more preferably 3 to 40% by mass, and still more preferably 5 to 30% by mass with respect to the fluororesin. Thereby, when the light with a wavelength of 400-1400 nm is radiated | emitted to the surface of A layer in the back surface protective film for solar cells of this invention, the reflectance with respect to this light can be 50% or more preferably. When there is too much content of the white colorant contained in a thermoplastic resin composition (IV), the flexibility of the back surface protective film for solar cells of this invention may fall.

  The thermoplastic resin composition (IV) may contain a colorant other than the white colorant (for example, a yellow colorant, a blue colorant, etc.). When using other colorants, the content thereof is usually 10% by mass or less with respect to the thermoplastic resin composition (IV).

  When the thermoplastic resin composition (IV) contains an additive, its specific compound and content will be described later.

  A commercially available fluororesin film can also be used for the D layer.

  The thickness of D layer is 10-300 micrometers normally, Preferably it is 15-250 micrometers, More preferably, it is 20-200 micrometers. When the thickness is too thin, the protective effect on the C-layer side surface of the solar cell back surface protective film of the present invention is insufficient, and when it is too thick, the flexibility of the solar cell back surface protective film is insufficient. .

<Laminated body (back surface protection film for solar cell)>
The preferable aspect in the back surface protection film for solar cells of this invention is shown below.

(I) A layer is an infrared transparent colored resin layer, B layer is a white resin layer, C layer is a white resin layer containing a white colorant, and D layer is colored other than white Or a film which is an uncolored resin layer.

(II) The A layer is an infrared transparent colored resin layer, the B layer is a white resin layer, the C layer is colored other than white, or is an uncolored resin layer, and the D layer is other than white A film that is colored or uncolored resin layer.

(III) The A layer is an infrared transparent colored resin layer, the B layer is a white resin layer, the C layer is a white resin layer containing a white colorant, and the D layer contains a white colorant A film that is a white resin layer.

(IV) The A layer is an infrared transparent colored resin layer, the B layer is a white resin layer, the C layer is colored other than white, or is an uncolored resin layer, and the D layer is white A film which is a white resin layer containing a colorant.

  In the back surface protective film of the present invention, the A layer 11, the B layer 12, the C layer 13 and the D layer 14 may be continuously laminated (see FIG. 1), or the A layer 11 and the B layer 12, B. The layer 12 and the C layer 13 and / or the C layer 13 and the D layer 14 may have a structure formed by bonding via an adhesive layer (not shown). In these cases, the configuration of the adhesive layer can be a polyurethane resin composition or the like.

  As a manufacturing method of the back surface protection film for solar cells of this invention, the method of joining the film for A layer formation, the film for B layer formation, the film for C layer formation, and the film for D layer formation is mentioned. As a specific method, four films are bonded at the same time (hereinafter referred to as “method (21)”), the A layer forming film and the B layer forming film are bonded, and then the C layer forming film. A method of joining a film and further joining a film for forming a D layer (hereinafter referred to as “method (22)”), a film for forming an A layer and a film for forming a B layer, and a film for forming a B layer; A method of joining these two laminated films (hereinafter referred to as “method (23)”) after joining the C-layer forming film is exemplified.

  In the case of the method (21), use of an adhesive, thermal fusion, dry lamination, or the like is applied.

  In the case of the method (22), the A layer forming film and the B layer forming film are joined by use of an adhesive, heat fusion, dry lamination, etc. to obtain a laminated film, and then the B layer in this laminated film. After forming the laminated film by bonding the surface on the forming film side and the film for forming the C layer by use of an adhesive, heat fusion, dry lamination, etc., the film on the C layer forming film side in this laminated film The surface and the D layer forming film can be bonded by use of an adhesive, heat fusion, dry lamination, or the like. Moreover, after obtaining the laminated | multilayer film which consist of A layer and B layer by the co-extrusion method (T die-cast film molding method etc.) using thermoplastic resin composition (I) and thermoplastic resin composition (II), After the surface of the B layer side of this laminated film and the C layer forming film are joined by use of an adhesive, heat fusion, dry lamination, etc., a laminated film is obtained, and then for the C layer formation in this laminated film The surface on the film side and the film for forming the D layer can be bonded by using an adhesive, heat sealing, dry lamination, or the like.

  Furthermore, in the case of the method (23), the B layer forming film and the C layer forming film are joined by using an adhesive, heat-sealing, dry laminating, etc. to obtain a laminated film, and then the B layer in this laminated film The surface on the side and the film for forming the A layer can be bonded by use of an adhesive, heat fusion, dry lamination or the like.

  When manufacturing the back surface protective film for solar cells of the present invention by other methods, for example, a thermoplastic resin composition (I), a thermoplastic resin composition (II), and a thermoplastic resin composition (III). By the co-extrusion method used (T-die cast film molding method etc.), the back surface protective film for solar cells in which the A layer, the B layer and the C layer are joined can be produced.

  The solar cell back surface protective film of the present invention is a water vapor layer between the A layer 11 and the B layer 12, between the B layer 12 and the C layer 13, and / or between the C layer 13 and the D layer 14. It can be set as the aspect provided with the barrier layer 15 (refer FIGS. 2-5).

The water vapor barrier layer has a water vapor transmission rate (hereinafter also referred to as “water vapor water vapor transmission rate”) of 3 g / (m ² · day) or less in accordance with JIS K7129, measured under conditions of a temperature of 40 ° C. and a humidity of 90% RH. The layer has a performance of preferably 1 g / (m ² · day) or less, more preferably 0.7 g / (m ² · day) or less. The water vapor barrier layer is preferably a layer made of an electrically insulating material.

  The water vapor barrier layer may have a single layer structure or a multilayer structure made of one kind of material, or may have a multilayer structure made of two or more kinds of materials. In this invention, it is preferable that it is a vapor deposition film by which the film | membrane which consists of a metal and / or a metal oxide is formed in the surface. Each of the metal and the metal oxide may be a single substance or two or more kinds.

  Examples of the metal include aluminum. Examples of the metal compound include oxides of elements such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, and yttrium. Of these, silicon oxide, aluminum oxide, and the like are particularly preferable from the viewpoint of water vapor barrier properties.

  The film made of a metal and / or a metal oxide can be formed by a method such as plating, vacuum deposition, ion plating, sputtering, plasma CVD, or microwave CVD. Two or more of these methods may be combined.

  Polyester film such as polyethylene terephthalate film and polyethylene naphthalate; polyolefin film such as polyethylene and polypropylene; polyvinylidene chloride film, polyvinyl chloride film, fluororesin film, polysulfone film, polystyrene film, polyamide film , Polycarbonate film, polyacryl nitrilo film, polyimide film and the like. The thickness of this resin film is usually 5 to 50 μm, preferably 8 to 20 μm.

  The water vapor barrier layer may be formed using a commercially available product. For example, “Tech Barrier AX” (trade name) manufactured by Mitsubishi Plastics, “Tech Barrier LX” (trade name), “GX Film” (trade name) manufactured by Toppan Printing Co., Ltd., “Ecosia VE500” (trade name) manufactured by Toyobo Co., Ltd. Can be used as a water vapor barrier layer forming sheet (or film).

  The arrangement of the water vapor barrier layer between the A layer and the B layer, between the B layer and the C layer, and / or between the C layer and the D layer is not particularly limited, and is a metal and / or metal oxide. The film made of may face any of the A layer, the B layer, the C layer, and the D layer.

  The water vapor barrier layer may be formed of a three-layer film in which a film made of metal and / or metal oxide is disposed between an upper layer side resin part and a lower layer side resin part.

  The thickness of the water vapor barrier layer is usually 5 to 300 μm, preferably 8 to 250 μm, and more preferably 10 to 200 μm. If the water vapor barrier layer is too thin, the water vapor barrier property may be insufficient, and if it is too thick, the flexibility as the back surface protective film for solar cell of the present invention may not be sufficient.

  When the back surface protective film for solar cells of the present invention includes a water vapor barrier layer, between the A layer and / or B layer, the water vapor barrier layer, between the B layer and / or C layer, and the water vapor barrier layer, An adhesive layer can be provided between the C layer and / or the D layer and the water vapor barrier layer. The configuration of the adhesive layer can be a polyurethane resin composition, an epoxy resin composition, an acrylic resin composition, or the like.

The following four types are mentioned as the back surface protective film for solar cells of this invention.
[P] A film comprising an A layer, a B layer, a C layer, and a D layer sequentially.
[Q] A film comprising an A layer, a water vapor barrier layer, a B layer, a C layer, and a D layer in this order.
[R] A film comprising an A layer, a B layer, a water vapor barrier layer, a C layer, and a D layer in this order.
[S] A film comprising an A layer, a B layer, a C layer, a water vapor barrier layer, and a D layer in this order.

[T] A film comprising an A layer, a water vapor barrier layer, a B layer, a water vapor barrier layer, a C layer, and a D layer in this order.
[U] A film comprising an A layer, a B layer, a water vapor barrier layer, a C layer, a water vapor barrier layer, and a D layer in this order.
[V] A film comprising an A layer, a water vapor barrier layer, a B layer, a C layer, a water vapor barrier layer, and a D layer in this order.
[W] A film comprising an A layer, a water vapor barrier layer, a B layer, a water vapor barrier layer, a C layer, a water vapor barrier layer, and a D layer in this order.

  The thickness of the back surface protective film for solar cells of the present invention is usually 30 to 900 μm, preferably 40 to 700 μm, more preferably from the viewpoint of flexibility, shape followability when disposed on other articles, workability, and the like. Preferably it is 50-600 micrometers.

  The back surface protective film for solar cells of the present invention is composed of the laminated film as described above, and one of the characteristics is that when light having a wavelength of 740 nm is radiated to the surface on the A layer side of the laminated film, reflection on the light is performed. The rate is 20% or more.

  Conventionally, carbon black that absorbs light having a wavelength in the infrared region is known as a dark colorant. When sunlight is received on the surface of the A layer of the back protective film for solar cells formed by using a composition using carbon black instead of the infrared transmitting colorant, the heat storage in the A layer is remarkable. It becomes. Therefore, the solar cell module is formed by bonding the surface on the layer A side of the back surface protective film for solar cells in this embodiment and the filler part containing the ethylene / vinyl acetate copolymer composition and the like embedding the solar cell element. When sunlight leaks into the A layer containing carbon black, the temperature of the filler material containing the solar cell element will be raised from the stored back surface protection film for solar cell, reducing the power generation efficiency. There is a bug to let you. Therefore, in the present invention, by using an infrared transmissive colorant mixture composed of at least two kinds of colorants instead of carbon black, low heat storage properties are maintained, and the above-described problems in solar cell applications and the like are suppressed. be able to.

  Further, Patent Document 2 mentioned above proposes the use of a perylene pigment as a dark colorant. As perylene pigments, commercially available products such as “Paligen Black S 0084”, “Palogen Black L 0086”, “Lumogen Black FK4280”, “Lumogen Black FK4281” (all of which are trade names manufactured by BASF) are known. ing. However, since such a perylene pigment absorbs light in the vicinity of a wavelength of 740 nm, in the case of a laminated film composed of a resin layer containing a perylene pigment, when radiated to the surface of the laminated film having a wavelength of 740 nm, The reflectance is less than 20%, and the power generation efficiency is insufficient.

  Furthermore, the above-mentioned Patent Document 3 proposes a colored resin layer having an absorptance of light having a wavelength of 800 to 1400 nm of 10% or less as the A layer similar to the present invention. Specifically, the proposal uses a perylene black pigment as the infrared transmitting colorant in the same manner as described above, but a combination of a perylene black pigment and another pigment is also proposed. That is, when a yellow pigment is used in combination with a perylene black pigment, a brown layer (A) is obtained, and when a blue pigment is used in combination, an amber layer (A) is obtained and a white pigment is combined. When used, a gray layer (A) is obtained. However, the proposal of the above combination in Patent Document 3 is a proposal under the condition that a colored resin layer having an absorption rate of light of a wavelength of 800 to 1400 nm of 10% or less is obtained, and a reflectance for light of a wavelength of 740 nm is obtained. It is not directly related to the present invention of 20% or more.

  The spectrum of sunlight is widely distributed from ultraviolet to infrared. And according to knowledge of the present inventors, the reflectance with respect to the said light at the time of radiating | emitting the light of wavelength 740nm to the surface by the side of A layer of the above-mentioned laminated film which comprises the back surface protection film for solar cells is 20% or more If the above characteristics are satisfied, excellent photoelectric conversion efficiency can be obtained. The reason is that the selective reflected light that is reflected by the B layer and introduced into the solar cell element, that is, the photoelectric that is transmitted without being absorbed by the A layer. This is thought to be due to an increase in the amount of light in the near-infrared band from visible light that can be converted.

  And as long as the amount of light in the near-infrared band from visible light that can be converted without being absorbed by the A layer satisfies each condition of the laminated film described above, as shown in many examples described below, By appropriately selecting an infrared transmitting colorant mixture composed of two kinds of colorants in the A layer, it can be increased, and the light in the case where light having a wavelength of 740 nm is emitted to the surface on the A layer side of the laminated film The characteristic that the reflectance with respect to is 20% or more can be satisfied. The reflectance is preferably 30% or more, more preferably 40% or more.

  In the preferable aspect of this invention, when the light of wavelength 400-700 nm is radiated | emitted to the surface at the side of A layer of a laminated | multilayer film, the absorptivity with respect to this light is 60% or more. The higher the absorptance, the lower the brightness of the laminated film as viewed from the A layer side, and a dark colored laminated film is formed. Thereby, when a transparent member or a translucent member and the surface of A layer are joined and a composite member is produced, it is excellent in the external appearance and designability seen from the transparent member side. For example, when a laminated film is used as a back sheet for a solar cell to produce a solar cell module and then used as a solar cell, the appearance and design of the solar cell disposed on the roof of a house are excellent.

  “Absorptivity with respect to light having a wavelength of 400 to 700 nm is 60% or more” means that the absorptance of light in the wavelength region from 400 nm to 700 nm is measured every 400 nm or from 700 nm to 20 nm, and each absorptivity is used. It means that the calculated average value is 60% or more, and it does not require that the light absorption rate in the wavelength range is 60% or more. The absorptance is preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more.

  In the preferable aspect of this invention, when the light of wavelength 800-1400nm is radiated | emitted on the surface by the side of A layer of a laminated | multilayer film, the reflectance with respect to this light is 50% or more. The higher the reflectivity, the more light having at least the wavelength can be reflected toward the A layer side. For example, when a laminated film is used as a solar cell backsheet to produce a solar cell module, at least light having the above wavelength can be reflected toward the solar cell element, thereby improving the photoelectric conversion efficiency. it can.

  “Reflectance for light with a wavelength of 800 to 1,400 nm is 50% or more” means that the reflectance of light in the wavelength range from 800 nm to 1,400 nm is measured every 800 nm or every 1,400 nm to 20 nm. In addition, it means that the average value calculated using each reflectance is 50% or more, and it does not require that all the reflectances of light in the wavelength range are 50% or more. The reflectance is preferably 60% or more, more preferably 70% or more.

  By providing the above-mentioned preferable performance, in the back surface protective film for solar cell of the present invention, preferably, 60% or more of light having a wavelength of 400 to 700 nm emitted to the surface of the A layer is absorbed, and a wavelength of 800 to When light having a wavelength of 1,400 nm is transmitted and this light reaches the B layer, the B layer can sufficiently reflect this light and suppress the occurrence of thermal deformation due to the light. Moreover, it was set as the solar cell module formed by adhere | attaching the surface by the side of A layer of the back surface protection film for solar cells of this invention, and the filling part which consists of an ethylene-vinyl acetate copolymer composition which embeds a solar cell element. In some cases, the reflected light can be used for photoelectric conversion to improve power generation efficiency.

  The above-mentioned property that the absorptance with respect to light having a wavelength of 400 to 700 nm is 60% or more and the above-mentioned property that the reflectance with respect to light with a wavelength of 800 to 1,400 nm is 50% or more are both many As shown in the examples, this can be achieved by appropriately selecting an infrared transmitting colorant mixture composed of two colorants in the A layer.

  The infrared transmissive colorant mixture in the present invention is a mixed colorant having the property of absorbing visible light and transmitting infrared light, and usually exhibits a color other than white, preferably black, brown, dark blue, It is a dark color such as dark green, and more preferably black.

  As the colorant constituting the colorant mixture, the film has an absorption peak only in a part of the visible light band and is transparent in the infrared band, and the film transmittance for light having a wavelength of 740 nm is usually 70. % Or more, preferably 80% or more, and more preferably 85% or more. Since these colorants are premised on exposure to sunlight, it is preferable to select those having the desired weather resistance, such as chrome yellow, titanium red, petal, vermilion, cadmium red, ultramarine, bitumen, Examples include cobalt blue, isoindolinone, quinacridone red, phthalocyanine blue, and indanthrene blue.

  In order to obtain black as an infrared transmitting colorant mixture, it is composed of at least two kinds of colorants. As the type of colorant, preferably anthraquinones, azos, anthrapyridones, perylenes, anthracenes, perinones, indanthrone, quinacridones, xanthenes, thioxanthenes, oxazines, oxazolines, Indigoids, thioindigoids, quinophthalones, naphthalimides, cyanines, methines, pyrazolones, lactones, coumarins, bis-benzoxazolylthiophenes, naphthalenetetracarboxylic acids, phthalocyanines, triarylmethanes, Amino ketones, bis (styryl) biphenyls, azines, rhodamines, derivatives of the foregoing, and mixtures thereof.

  Among the at least two colorants, specific dyes include red dyes, orange dyes, yellow dyes, green dyes, blue dyes, and purple dyes.

  Examples of red dyes include solvent red 1, solvent red 8, solvent red 23, solvent red 24, solvent red 25, solvent red 49, solvent red 52, solvent red 109, solvent red 111, solvent red 119, solvent red 122, Solvent Red 132, Solvent Red 135, Solvent Red 145, Solvent Red 146, Solvent Red 149, Solvent Red 179, Solvent Red 195, Solvent Red 196, Solvent Red 197, Solvent Red 207, Solvent Red 218, Solvent Red 242 and the like It is done.

  Examples of orange dyes include Solvent Orange 3, Solvent Orange 14, Solvent Orange 45, Solvent Orange 54, Solvent Orange 60, Solvent Orange 62, Solvent Orange 63, Solvent Orange 86, Solvent Orange 107, Disperse Orange 47, and the like. It is done.

  Examples of yellow dyes include solvent yellow 14, solvent yellow 16, solvent yellow 18, solvent yellow 19, solvent yellow 21, solvent yellow 33, solvent yellow 56, solvent yellow 82, solvent yellow 93, solvent yellow 98, solvent yellow 114, Solvent Yellow 145, Solvent Yellow 160, Solvent Yellow 163, Solvent Yellow 176, Disperse Yellow 54, Disperse Yellow 64, Disperse Yellow 160, Disperse Yellow 201, Disperse Yellow 211, and the like.

  Examples of green dyes include Solvent Green 3, Solvent Green 5, Solvent Green 20, Solvent Green 28, and the like.

  Examples of blue dyes include solvent blue 4, solvent blue 5, solvent blue 6, solvent blue 35, solvent blue 36, solvent blue 38, solvent blue 59, solvent blue 70, solvent blue 78, solvent blue 97, solvent blue 104, Solvent blue 122 etc. are mentioned.

  Examples of purple dyes include solvent violet 8, solvent violet 9, solvent violet 13, solvent violet 26, solvent violet 28, solvent violet 31, solvent violet 36, solvent violet 37, solvent violet 56, and the like.

  The mixing ratio of the colorant mixture is usually roughly equal to each colorant (1: 1 in the case of two types, and 1: 1 in the case of four types, each of the two complementary colors). Is basically increased or decreased according to the desired dark hue or according to the color mixing characteristics of the colorant. For example, in the case of four types, one of the two colors in the complementary color relationship can be 1: 1, and the other two colors in the complementary color relationship can be 0.5: 0.5, etc. There is no need for equal amounts of colorant. The addition amount of the colorant mixture is usually 0.1 to 20% by weight, preferably 0.2 to 15% by weight, more preferably 0.3 to 10% by weight, based on the thermoplastic resin. Specifically, it is added to a thermoplastic resin and formed in a predetermined layer thickness, preferably has a transmittance of 70% or more in the entire infrared band, and has a desired dark color in the visible light band. The amount added is adjusted as appropriate.

  The dark color means a chromatic color or achromatic color having a low lightness such as brown, amber, dark green, etc. in addition to black, and a color having an absorption spectrum over the entire band of the visible light range. There are at least two types of colorants to be combined. In the case of two types, colorants having hues having a so-called “complementary color” relationship are combined. For example, when a green colorant and a red colorant are combined, the green color hue symbol is usually 1 GY to 10BG, preferably 5 GY to 5BG, and the red color hue symbol is usually 1RP-10YR, preferably 5RP-5YR. When a purple colorant and a yellow colorant are combined, the purple color hue symbol is usually 1PB to 10RP, preferably 5PB to 5RP, and the yellow color hue symbol is usually 1YR to 10 GY, preferably 5 YR to 5 GY. In the case of combining an orange colorant and a blue colorant, the hue symbol of the orange color is usually 5R-5Y, preferably 1YR-10YR, and the hue of the blue color The symbol is usually 1BG to 10PB, preferably 5BG to 5PB.

  In the case of three or more types, for example, a combination of a yellow colorant, a red colorant, and a blue colorant is selected so as to satisfy the entire visible light band when combining three types of absorption spectra. To do. The three colorants are selected so that the hue symbols of the colors are different from each other.

  In the case of four or more types, for example, four types of absorption spectra were synthesized by using a combination of a red colorant and a green colorant and a combination of a purple colorant and a yellow colorant. Sometimes it is chosen to fill the full band of visible light. The four colorants are selected so that the hue symbols of the colors are different from each other.

  In the present invention, it is preferable to use at least three colorants, and it is more preferable to use at least four colorants. For example, a combination of a red colorant (hue symbol: usually 1RP to 10YR, preferably 5RP-5YR) and a green colorant (hue symbol: usually 1GY to 10BG, preferably 5GY to 5BG), a purple color (hue) Symbol: Usually a combination of a colorant of 1PB to 10RP, preferably 5PB to 5RP) and a yellow colorant (hue symbol: usually 1YR to 10GY, preferably 5YR to 5GY), and an orange color (hue symbol) : Usually a combination of at least two dyes selected from a combination of a colorant of 5R to 5Y, preferably 1YR to 10YR and a colorant of a blue color (hue symbol: usually 1BG to 10PB, preferably 5BG to 5PB). Inclusion is more preferable. Each colorant is selected so that the hue symbols of the colors are different from each other.

  The at least two colorants are preferably at least two dyes, such as a solvent red dye, a solvent green dye, a solvent violet dye, a solvent yellow dye or a disperse yellow dye, and a solvent orange dye. Preferably it comprises a combination of at least one dye selected from the group consisting of solvent blue dyes. Further, it is preferable that the at least two kinds of dyes include a combination of at least two kinds of dyes, and a combination of at least three kinds of dyes.

  When at least two kinds of colorants contain two kinds of colorants having a complementary color relationship, the weight ratio of these two kinds of colorants is usually about 0.5 to 2, preferably about 0.7 to 1.5. It is preferable that

  The A layer is a dark resin layer, and the L value (brightness) on the surface of the film is usually 50 or less, preferably 40 or less, more preferably 35 or less.

Moreover, when the back surface protective film for solar cells of this invention is aspect [Q], [R], [S], [T], [U], [V], and [W], the A layer side and D layer When the water vapor permeability of the back surface protective film for solar cells is measured under conditions of a temperature of 40 ° C. and a humidity of 90% RH according to JIS K7129, it is usually 3 g / (m ² · day). ) Or less, preferably 1 g / (m ² · day) or less. Because of having the above performance, when a solar cell module is produced using the back surface protective film for solar cells of the present invention, the deterioration of the solar cell element due to the intrusion of water, water vapor, etc., and further the reduction in power generation efficiency It can be suppressed and has excellent durability.

  Furthermore, the back surface protective film for solar cells of the present invention is excellent in heat resistance. For example, when left at 135 ° C. for 30 minutes, the dimensional change rate before and after that is usually ± 1.5% or less, preferably ± 1. 2% or less, more preferably ± 1.0% or less.

  In the present invention, layer A (thermoplastic resin composition (I)), layer B (thermoplastic resin composition (II)), layer C (thermoplastic resin composition (III), unless the effects of the present invention are impaired. )) And D layer (thermoplastic resin composition (IV)) may contain various additives (other colorants, antioxidants, ultraviolet absorbers, anti-aging agents, plasticizers, flame retardants). I can do it.

  Examples of the antioxidant include hindered amine compounds, hydroquinone compounds, hindered phenol compounds, sulfur-containing compounds, and phosphorus-containing compounds. Two or more of these may be used. The content of the antioxidant is usually 0.00 with respect to the thermoplastic resin composition (I), the thermoplastic resin composition (II), the thermoplastic resin composition (III) or the thermoplastic resin composition (IV). 05 to 10% by mass.

  Examples of ultraviolet absorbers include benzophenone compounds, benzotriazole compounds, and triazine compounds. Two or more of these may be used. The content of the ultraviolet absorber is usually 0.00 with respect to the thermoplastic resin composition (I), the thermoplastic resin composition (II), the thermoplastic resin composition (III) or the thermoplastic resin composition (IV). 05 to 10% by mass.

  Examples of the anti-aging agent include amine compounds, quinoline compounds, hydroquinone derivative compounds, phenol compounds, hindered phenol compounds, phosphite compounds, imidazole compounds, and phosphate compounds. Two or more of these may be used. The content of the anti-aging agent is usually 0.00 with respect to the thermoplastic resin composition (I), the thermoplastic resin composition (II), the thermoplastic resin composition (III) or the thermoplastic resin composition (IV). 05 to 10% by mass.

  Examples of the plasticizer include phthalic acid esters; fatty acid esters; trimellitic acid esters. Two or more of these may be used. The content of the plasticizer is usually 0.05 with respect to the thermoplastic resin composition (I), the thermoplastic resin composition (II), the thermoplastic resin composition (III), or the thermoplastic resin composition (IV). -10 mass%.

  Examples of the flame retardant include organic flame retardants, inorganic flame retardants, and reactive flame retardants. Two or more of these may be used.

  Examples of organic flame retardants include halogenated flame retardants such as brominated epoxy compounds, brominated bisphenol epoxy resins and brominated polystyrene resins; phosphate esters such as trimethyl phosphate, compounds obtained by modifying these with various substituents, various And phosphorous flame retardants such as phosphazene derivatives containing phosphorus and nitrogen elements; polytetrafluoroethylene, guanidine salts, silicone compounds, phosphazene compounds, and the like. Two or more of these may be used.

  Examples of the inorganic flame retardant include aluminum hydroxide, antimony oxide, magnesium hydroxide, zinc borate and the like. Two or more of these may be used.

  Examples of the reactive flame retardant include tetrabromobisphenol A and dibromophenol glycidyl ether. Two or more of these may be used.

  The content of the flame retardant is usually 10% by mass with respect to the thermoplastic resin composition (I), the thermoplastic resin composition (II), the thermoplastic resin composition (III) or the thermoplastic resin composition (IV). It is as follows.

  In addition, when making a thermoplastic resin composition contain a flame retardant, it is preferable to use a flame retardant aid. Examples of the flame retardant aid include antimony compounds such as antimony trioxide, zinc borate, barium metaborate, hydrated alumina, zirconium oxide, ammonium polyphosphate, and tin oxide. Two or more of these may be used.

  In addition, between the A layer and the B layer, between the B layer and the C layer, and / or between the C layer and the D layer in the solar cell back surface protective film of the present invention, If desired, other layers such as a transparent resin layer, a decorative layer, a coating layer, and a layer made of a recycled resin produced during production can be provided as long as the effects of the present invention are not impaired.

  The method for producing the solar cell back surface protective film of the present invention is not particularly limited, and is selected depending on the constituent material of each layer, that is, each thermoplastic resin composition.

  The film of aspect [P] is as the manufacturing method of the back surface protection film for solar cells of this invention.

  As a method for producing the film of aspect [Q], for example, after the A layer forming film and the water vapor barrier layer forming film are bonded by heat fusion, dry lamination, or adhesive, the first laminated film is obtained. The water vapor barrier layer side surface in this first laminated film and the B layer forming film are joined with an adhesive to form a second laminated film, and then the B layer side surface in this second laminated film, and the C layer A method of joining the forming film with an adhesive to form a third laminated film, and then joining the C layer side surface of the third laminated film and the D layer forming film with an adhesive, etc. Can be mentioned.

  As a manufacturing method of the film of aspect [R], for example, after producing the 1st lamination film which consists of A layer and B layer, the B layer side surface in this 1st lamination film, and the film for water vapor barrier layer formation The second laminated film is bonded by heat fusion or dry lamination or an adhesive, and then the water vapor barrier layer side surface of the second laminated film is bonded to the C layer forming film by an adhesive. Examples of the method include a method of joining the C layer side surface of the third laminated film and the D layer forming film with an adhesive, and the like.

  Moreover, as a manufacturing method of the film of aspect [S], for example, after producing the 1st laminated film which consists of A layer and B layer, the B layer side surface in this 1st laminated film, and C layer formation The film is bonded by heat fusion or dry lamination or an adhesive to form a second laminated film, and then the C layer side surface of the second laminated film and the water vapor barrier layer forming film are bonded by an adhesive. And a method of joining the surface of the water vapor barrier layer in the third laminated film and the D layer forming film with an adhesive, and the like.

  As a manufacturing method of the film of aspect [U], for example, after producing the 1st lamination film which consists of A layer and B layer, the B layer side surface in this 1st lamination film, and the film for water vapor barrier layer formation The second laminated film is bonded by thermal fusion or dry lamination or an adhesive, and then the water vapor barrier layer side surface of the second laminated film and the C layer forming film are thermally fused or dry laminated or Bonded with an adhesive to form a third laminated film, and then the C layer side surface of the third laminated film and the water vapor barrier layer forming film are bonded with an adhesive to form a fourth laminated film, and then Examples include a method of bonding the water vapor barrier layer side surface of the fourth laminated film and the D layer forming film with an adhesive.

  As a method for producing the film of the embodiment [W], for example, after the A layer forming film and the water vapor barrier layer forming film are bonded by heat fusion, dry lamination, or adhesive, the first laminated film is obtained. The water vapor barrier layer side surface in the first laminated film and the B layer forming film are joined with an adhesive to form a second laminated film, and then the B layer side surface in the second laminated film, and the water vapor barrier The layer forming film is bonded by heat fusion or dry lamination or an adhesive to form a third laminated film, and then the water vapor barrier layer side surface of the third laminated film is bonded to the C layer forming film. The fourth laminated film is joined by an agent, and then the water vapor barrier layer side surface of the fourth laminated film and the D layer forming And Irumu method and the like to be bonded with an adhesive.

<Solar cell module>
When using the back surface protection film for solar cells of this invention as a solar cell backsheet, the schematic of a solar cell module provided with the back surface protection film of this invention is shown by FIG.

  The solar cell module 2 in FIG. 6 includes a surface-side transparent protective member 21, a surface-side sealing film (surface-side filler) 23, a solar cell element 25, and a back surface side from the sunlight receiving surface side (upper side in the drawing). The sealing film (back surface side filler material part) 27 and the back surface protective film 1 of the present invention can be disposed in this order. In addition, the solar cell module of this invention can also be equipped with various members as needed other than the said component as needed as needed (not shown).

The surface-side transparent protective member 21 is preferably made of a material having excellent water vapor barrier properties, and a transparent substrate made of glass, resin or the like is usually used. In addition, although glass is excellent in transparency and weather resistance, since impact resistance is not enough and it is heavy, when it is set as the solar cell mounted on the roof of a house, it is preferable to use a weather resistant transparent resin. Examples of the transparent resin include a fluorine-based resin.
The thickness of the surface side transparent protective member 21 is usually about 1 to 5 mm when glass is used, and is usually about 0.1 to 5 mm when transparent resin is used.

  The solar cell element 25 has a power generation function by receiving sunlight. As such a solar cell element, if it has a function as a photovoltaic power, it will not be specifically limited, A well-known thing can be used. For example, a crystalline silicon solar cell element such as a single crystal silicon type solar cell element or a polycrystalline silicon type solar cell element; an amorphous silicon solar cell element composed of a single bond type or a tandem structure type; gallium arsenide (GaAs) or indium phosphorus ( III-V compound semiconductor solar cell elements such as InP); II-VI compound semiconductor solar cell elements such as cadmium tellurium (CdTe) and copper indium selenide (CuInSe2). Of these, a crystalline silicon solar cell element is preferable, and a polycrystalline silicon solar cell element is particularly preferable. A thin film polycrystalline silicon solar cell element, a thin film microcrystalline silicon solar cell element, a hybrid element of a thin film crystalline silicon solar cell element and an amorphous silicon solar cell element, or the like can be used.

  In FIG. 6, although not shown, the solar cell element 25 normally includes a wiring electrode and an extraction electrode. The wiring electrode has an action of collecting electrons generated in the plurality of solar cell elements by receiving sunlight, for example, a solar cell element on the surface side sealing film (surface side filler part) 21 side, It connects so that the solar cell element by the side of the back surface side sealing film (back surface side filler material part) 27 side may be connected. The take-out electrode has an action of taking out electrons collected by the wiring electrode or the like as a current.

  The front-side sealing film (front-side filler part) 21 and the back-side sealing film (back-side filler part) 27 (hereinafter collectively referred to as “sealing film”) are usually the same or different from each other. After making into a sheet-like or film-like sealing film in advance using the film-forming material, the solar cell element 25 and the like are thermocompression bonded between the surface-side transparent protective member 21 and the solar cell back surface protective film 1. Formed.

  The thickness of each sealing film (filler part) is usually about 100 μm to 4 mm, preferably about 200 μm to 3 mm, and more preferably about 300 μm to 2 mm. If the thickness is too thin, the solar cell element 25 may be damaged. On the other hand, if the thickness is too thick, the manufacturing cost increases, which is not preferable.

  The sealing film forming material is usually a resin composition or a rubber composition. Examples of the resin include an olefin resin, an epoxy resin, a polyvinyl butyral resin, and the like. Examples of the rubber include silicone rubber and hydrogenated conjugated diene rubber. Of these, olefin resins and hydrogenated conjugated diene rubbers are preferred.

  Examples of olefin resins include olefins such as ethylene, propylene, butadiene, and isoprene, or polymers obtained by polymerizing diolefins, and ethylene and other monomers such as vinyl acetate and acrylate esters. Copolymers, ionomers and the like can be used. Specific examples include polyethylene, polypropylene, polymethylpentene, ethylene / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid ester copolymer, ethylene / vinyl alcohol copolymer, chlorine. Examples thereof include chlorinated polyethylene and chlorinated polypropylene. Among these, an ethylene / vinyl acetate copolymer and an ethylene / (meth) acrylic acid ester copolymer are preferable, and an ethylene / vinyl acetate copolymer is particularly preferable.

  Examples of hydrogenated conjugated diene rubber include hydrogenated styrene / butadiene rubber, styrene / ethylene butylene / olefin crystal block polymer, olefin crystal / ethylene butylene / olefin crystal block polymer, styrene / ethylene butylene / styrene block polymer, and the like. It is done.

  Sealing film forming materials include crosslinking agents, crosslinking aids, silane coupling agents, UV absorbers, hindered phenolic and phosphite antioxidants, hindered amine light stabilizers, and light diffusion as required. Additives such as an agent, a flame retardant, and a discoloration inhibitor can be contained.

  As described above, the material forming the front surface side sealing film (front surface side filler part) 23 and the material forming the back surface side sealing film (back surface side filler part) 27 are the same or different. However, the same is preferable from the viewpoint of adhesiveness.

  The solar cell module of the present invention includes, for example, a surface side transparent protective member, a surface side sealing film, a solar cell element, a back surface side sealing film, and a solar cell back surface protective film according to the present invention arranged in this order. Can be manufactured by a lamination method or the like in which heat is pressure-bonded with vacuum suction. The lamination temperature in this lamination method is usually about 100 ° C. to 250 ° C. from the viewpoint of adhesiveness of the back protective film for solar cells of the present invention. The laminating time is usually about 3 to 30 minutes.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. In the following, “part” and “%” are based on mass unless otherwise specified.

<Evaluation method>
The measurement methods for various evaluation items are shown below.

(1) Rubber content in rubber-containing aromatic vinyl resin:
The ratio of the total amount of all rubber components to the total amount of rubber-containing aromatic vinyl resin was calculated.

(2) N-phenylmaleimide unit content in rubber-containing aromatic vinyl resin:
The ratio of the amount of N-phenylmaleimide units to the total amount of structural units constituting the rubber-containing aromatic vinyl resin was calculated.

(3) Reflectance (%) for light having a wavelength of 740 nm
The reflectance was measured with an ultraviolet-visible near-infrared spectrophotometer “V-670” (model name) manufactured by JASCO Corporation, using a back surface protective film (50 mm × 50 mm, thickness shown in the table) as a measurement sample. That is, light was emitted to the surface of the A layer of the measurement sample, and the reflectance at a wavelength of 740 nm was measured.

(4) Absorptivity (%) for light having a wavelength of 400 to 700 nm:
Using a back protective film (50 mm x 50 mm, thickness shown in the table) as a measurement sample, the transmittance and reflectance are measured with an ultraviolet-visible near-infrared spectrophotometer “V-670” (model name) manufactured by JASCO Corporation. did. That is, light was emitted to the surface of the A layer of the measurement sample, and the transmittance and reflectance in the wavelength region from 400 nm to 700 nm were measured every 20 nm, and the average value thereof was calculated. The absorptance was calculated by the following formula using the average value of transmittance and the average value of reflectance.
[Equation 2]
Absorptivity (%) = 100− {transmittance (%) + reflectance (%)}

(5) Reflectance (%) for light having a wavelength of 800 to 1,400 nm:
The reflectance was measured with an ultraviolet-visible near-infrared spectrophotometer “V-670” (model name) manufactured by JASCO Corporation, using a back surface protective film (50 mm × 50 mm, thickness shown in the table) as a measurement sample. That is, light was emitted to the surface of the A layer of the measurement sample, the reflectance in the wavelength region from 800 nm to 1,400 nm was measured every 20 nm, and the average value thereof was calculated.

(6) Photoelectric conversion efficiency improvement rate:
Using a super solar simulator “WXS-155S-10AM1.5GMM” (model name) manufactured by Wacom Denso Co., Ltd. in a room adjusted to a temperature of 23 ° C. ± 2 ° C. and a humidity of 50 ± 5% RH 3mm thick glass is placed on the surface of the cell (100mm x 100mm), the back surface protective film for solar cells is placed on the back surface, the silicon cell is sandwiched, and EVA is introduced between the glass and the film. The silicon cell was sealed to produce a solar cell module. Then, in order to reduce the influence of temperature, the photoelectric conversion efficiency was measured immediately after the light irradiation. Using the photoelectric conversion efficiency (A) of the module at a backsheet open rate of 14% and the photoelectric conversion efficiency (B) of the module at a backsheet open rate of 0%, the photoelectric conversion efficiency improvement rate was determined. However, the backsheet opening rate = (backsheet opening area / cell area) × 100.
[Equation 3]
Photoelectric conversion efficiency improvement rate (%) = {((A) − (B)) ÷ (B)} × 100

(7) Dark appearance:
The surface of the layer A in the back surface protective film for solar cells (50 mm × 50 mm, thickness is shown in the table) was visually observed. “3” if the color is deep black, “2” if it is a black color mixed with other colors (brown black, purple black, green black, etc.), gray The case was evaluated as “1”.

(8) L value:
Using a spectrophotometer “V-670” (model name) manufactured by JASCO Corporation, the L value of the surface of the A layer and the surface of the C layer in the back protective film for solar cells (50 mm × 50 mm, thickness is shown in the table) It was measured.

(9) Adhesion with EVA film:
As described above, when the solar cell back surface protective film is used as a member constituting the solar cell module, the film is formed by embedding the surface of the A layer and the solar cell element included in the solar cell module. It is used for bringing the back surface side sealing film into close contact. Since the ethylene / vinyl acetate copolymer composition is widely used as a material for forming the back surface side sealing film, the adhesion between the surface of the layer A in the back surface protective film for solar cells and the following EVA film is evaluated. did.

  The back surface protective film for solar cells was cut into a strip shape (200 mm × 15 mm, thickness is shown in the table) to obtain two evaluation films. An EVA film (trade name “Ultra Pearl”, manufactured by Sanvic Co., Ltd.) having a length of 100 mm, a width of 15 mm and a thickness of 400 μm made of an ethylene / vinyl acetate copolymer is located between the A layers of the two evaluation films. And placed in a laminator in a laminated state. Thereafter, the upper and lower portions of the laminator were evacuated and preheated at 150 ° C. for 5 minutes. Next, the upper part was returned to atmospheric pressure and pressed for 15 minutes to obtain a sample for measuring peel strength. In the obtained peel strength measurement sample, the peel strength was measured by peeling the T-shape from the portion where the evaluation film was not in close contact with the EVA film. Further, the peeled state was visually observed and judged according to the following criteria.

“2”: The film was broken.
“1”: Peeled at the interface between the EVA film and the evaluation film.

(10) Flexibility:
A solar cell back surface protective film (thickness is listed in the table) was cut to prepare a test piece having a size of 100 mm (MD) × 100 mm (TD). Next, after bending along the symmetry axis in the MD direction, bending was performed along the symmetry axis in the TD direction. The folded test piece was reciprocated twice on each crease at a speed of 5 mm / sec using a manual crimping roll (2,000 g) according to JIS Z0237. Thereafter, the folds were widened to return to the original state, the test piece was visually observed, and judged according to the following criteria. Those in which the folds are not broken are excellent in flexibility.

“3”: The crease was not broken, and the crease did not break even if it was folded or expanded again.
“2”: The crease was not broken, but the crease was broken when folded and expanded again.
“1”: The crease was broken.

(11) Flame retardancy:
A solar cell back sheet (20 mm x 100 mm, thickness is listed in the table) is used as a test piece, this test piece is suspended vertically, and a UL94 V test burner is used to separate the test piece from the burner tip to the test piece bottom by 10 mm. In this state, the lower end of the test piece was indirectly flamed for 5 seconds. After the completion of flame contact, the combustion state of the flame contact portion of the test piece was visually observed and judged according to the following criteria.

“2”: There was no ignition.
“1”: ignited.

(12) Water vapor barrier property:
In accordance with JIS K7129B, water vapor permeability was measured with a water vapor permeability measuring device “PERMATRAN W3 / 31” (model name) manufactured by MOCON. The measurement conditions were a temperature of 40 ° C. and a humidity of 90% RH, and the surface on the C layer side was disposed on the water vapor side as the transmission surface.

<Production raw material for back surface protection film for solar cell>
(1) Silicone / acrylic composite rubber reinforced aromatic vinyl resin (rubber reinforced resin (A1-1)):
“Metablene SX-006” (trade name) manufactured by Mitsubishi Rayon Co., Ltd. was used. This is a resin obtained by grafting an acrylonitrile / styrene copolymer onto a silicone / acrylic composite rubber. The content of the silicone / acrylic composite rubber is 50%, the graft ratio is 80%, the intrinsic viscosity [η] of acetone-soluble component (30 ° C. in methyl ethyl ketone) is 0.38 dl / g, and the glass transition temperature (Tg) is 135. ° C.

(2) Silicone rubber reinforced aromatic vinyl resin (rubber reinforced resin (A1-2)):
What was manufactured by the following method was used.

  1.3 parts of p-vinylphenylmethyldimethoxysilane and 98.7 parts of octamethylcyclotetrasiloxane are mixed, and this is put into 300 parts of distilled water in which 2.0 parts of dodecylbenzenesulfonic acid is dissolved, and 3 parts by a homogenizer. The mixture was stirred and dispersed for emulsification. This emulsified dispersion was transferred to a separable flask equipped with a condenser, a nitrogen inlet and a stirrer, and heated at 90 ° C. for 6 hours while stirring. Subsequently, it was kept at 5 ° C. for 24 hours to complete the condensation, and a latex containing a polyorganosiloxane rubber was obtained. The condensation rate was 93%. Thereafter, the latex was neutralized to pH 7 using an aqueous sodium carbonate solution. The obtained polyorganosiloxane rubber had a volume average particle size of 300 nm.

  Next, in a 7-liter glass flask equipped with a stirrer, 100 parts of ion exchange water, 1.5 parts of potassium oleate, 0.01 parts of potassium hydroxide, 0.1 part of tert-dodecyl mercaptan, A batch polymerization component consisting of a latex adjusted to pH 7 containing 40 parts of an organosiloxane rubber, 15 parts of styrene and 5 parts of acrylonitrile was added, and the temperature was raised while stirring. When the temperature reaches 45 ° C., the activity consists of 0.1 parts of sodium ethylenediaminetetraacetate, 0.003 parts of ferrous sulfate, 0.2 parts of sodium formaldehyde sulfoxylate dihydrate and 15 parts of ion-exchanged water. Aqueous agent aqueous solution and 0.1 part of diisopropylbenzene hydroperoxide were added and polymerization was carried out for 1 hour.

  Thereafter, 50 parts of ion exchange water, 1 part of potassium oleate, 0.02 part of potassium hydroxide, 0.1 part of tert-dodecyl mercaptan, 0.2 part of diisopropylbenzene hydroperoxide, 30 parts of styrene and An incremental polymerization component consisting of 10 parts of acrylonitrile was continuously added over 3 hours to continue the polymerization. After completion of the addition, stirring was further continued. After 1 hour, 0.2 part of 2,2′-methylenebis (4-ethyl-6-tert-butylphenol) was added to terminate the polymerization, and a silicone rubber reinforced aromatic vinyl resin (rubber reinforced resin A1-2). A latex containing was obtained.

  Next, 1.5 parts of sulfuric acid is added to the latex so that the resin component is solidified at 90 ° C., and then the resin component is washed with water, dehydrated and dried to obtain a silicone rubber reinforced aromatic vinyl resin (rubber reinforced resin). A1-2) was obtained. Glass transition temperature (Tg) is 108 ° C., polyorganosiloxane rubber content is 40%, graft rate is 84%, and acetone-soluble intrinsic viscosity [η] (in methyl ethyl ketone, 30 ° C.) is 0.60 dl / g.

(3) Acrylic rubber reinforced aromatic vinyl resin (rubber reinforced resin (A1-3)):
The reactor contains an acrylic rubbery polymer (volume average particle size: 100 nm, gel content: 90%) obtained by emulsion polymerization of 99 parts of n-butyl acrylate and 1 part of allyl methacrylate. 50 parts of latex having a solid content concentration of 40% (in terms of solid content) was added, and further diluted with 1 part of sodium dodecylbenzenesulfonate and 150 parts of ion-exchanged water. Thereafter, the inside of the reactor was replaced with nitrogen gas, and 0.02 part of disodium ethylenediaminetetraacetate, 0.005 part of ferrous sulfate and 0.3 part of sodium formaldehydesulfoxylate were added, and the mixture was stirred up to 60 ° C. The temperature rose.

  On the other hand, 50 parts of a mixture of 37.5 parts of styrene and 12.5 parts of acrylonitrile, 1.0 part of terpinolene and 0.2 part of cumene hydroperoxide are placed in a container, and the inside of the container is replaced with nitrogen gas. A mass composition was obtained.

  Next, the monomer composition was added to the reactor at a constant flow rate over 5 hours, and polymerization was performed at 70 ° C. to obtain a latex. Magnesium sulfate was added to this latex to coagulate the resin component. Then, acrylic rubber reinforced aromatic vinyl resin (rubber reinforced resin A1-3) was obtained by washing with water and drying. The content of the acrylic rubbery polymer is 50%, the graft ratio is 93%, the intrinsic viscosity [η] (30 ° C. in methyl ethyl ketone) of the acetone-soluble component is 0.30 dl / g, and the glass transition temperature (Tg) is It was 108 ° C.

(4) Silicone rubber reinforced aromatic vinyl resin (rubber reinforced resin (A1-4)):
1.3 parts of p-vinylphenylmethyldimethoxysilane and 98.7 parts of octamethylcyclotetrasiloxane are mixed, and this is put into 300 parts of distilled water in which 2.0 parts of dodecylbenzenesulfonic acid is dissolved, and 3 parts by a homogenizer. The mixture was stirred and dispersed for emulsification. This emulsified dispersion was transferred to a separable flask equipped with a condenser, a nitrogen inlet and a stirrer, and heated at 90 ° C. for 6 hours while stirring. Subsequently, it was kept at 5 ° C. for 24 hours to complete the condensation, and a latex containing a polyorganosiloxane rubber was obtained. The condensation rate was 93%. Thereafter, the latex was neutralized to pH 7 using an aqueous sodium carbonate solution. The obtained polyorganosiloxane rubber had a volume average particle size of 300 nm.

  Next, in a 7-liter glass flask equipped with a stirrer, 100 parts of ion exchange water, 1.5 parts of potassium oleate, 0.01 parts of potassium hydroxide, 0.3 part of tert-dodecyl mercaptan, A batch polymerization component consisting of a latex adjusted to pH 7 containing 18 parts of an organosiloxane rubber, 18 parts of styrene and 6 parts of acrylonitrile was added, and the temperature was raised while stirring. When the temperature reaches 45 ° C., the activity consists of 0.1 parts of sodium ethylenediaminetetraacetate, 0.003 parts of ferrous sulfate, 0.2 parts of sodium formaldehyde sulfoxylate dihydrate and 15 parts of ion-exchanged water. Aqueous agent aqueous solution and 0.03 part of diisopropylbenzene hydroperoxide were added and polymerization was carried out for 1.5 hours.

  Thereafter, 50 parts of ion-exchanged water, 1 part of potassium oleate, 0.02 part of potassium hydroxide, 0.3 part of tert-dodecyl mercaptan, 0.08 part of diisopropylbenzene hydroperoxide, 45.5 of styrene were added to the above reaction system. An incremental polymerization component consisting of 15.5 parts of acrylonitrile and 15.5 parts of acrylonitrile was continuously added over 3 hours to continue the polymerization. After completion of the addition, stirring was further continued. After 1 hour, 0.2 part of 2,2′-methylenebis (4-ethyl-6-tert-butylphenol) was added to complete the polymerization, and a silicone rubber reinforced aromatic vinyl resin (rubber reinforced resin A1-4). A latex containing was obtained. Next, 1.5 parts of sulfuric acid is added to the latex so that the resin component is solidified at 90 ° C., and then the resin component is washed with water, dehydrated and dried to obtain a silicone rubber reinforced aromatic vinyl resin (rubber reinforced resin). A1-4) was obtained. The glass transition temperature (Tg) is 108 ° C., the content of the polyorganosiloxane rubber is 40%, the graft ratio is 40%, and the intrinsic viscosity [η] (30 ° C. in methyl ethyl ketone) of the acetone soluble component is 0.40 dl / g.

(5) Acrylonitrile / styrene copolymer (A2-1):
AS polymer “SAN-H” (trade name) manufactured by Techno Polymer Co., Ltd. was used. The glass transition temperature (Tg) is 108 ° C.

(6) Acrylonitrile / styrene / N-phenylmaleimide copolymer (A2-2):
An acrylonitrile / styrene / N-phenylmaleimide copolymer “Polyimilex PAS1460” (trade name) manufactured by Nippon Shokubai Co., Ltd. was used. The amount of N-phenylmaleimide units is 40%, the amount of acrylonitrile units is 9%, the amount of styrene units is 51%, and the Mw in terms of polystyrene by GPC is 120,000. The glass transition temperature (Tg) is 173 ° C.

(7) Red colorant (R):
Solvent Red 52 was used.

(8) Yellow colorant (Y):
Solvent Yellow 163 was used.

(9) Green colorant (G):
Solvent Green 3 was used.

(10) Purple colorant (P):
Solvent violet 13 was used.

(11) Black colorant:
A perylene-based black pigment “Lumogen BLACK FK4280” (trade name) manufactured by BASF was used.

(12) Yellow colorant:
A BASF quinophthalone yellow pigment “Pariotol Yellow K0961HD” (trade name) was used.

(13) Carbon black:
“Carbon black # 45” (trade name) manufactured by Mitsubishi Chemical Corporation was used.

(14) White colorant Titanium oxide “Taipeke CR-60-2” (trade name) manufactured by Ishihara Sangyo Co., Ltd. was used. The average primary particle size is 0.21 μm.

(15) C layer forming film (W1):
A PET film “Teijin Tetron Film VW” (trade name) manufactured by Teijin DuPont was used. The thickness is 50 μm. This film is a laminated film comprising a translucent PET layer having a thickness of 35 μm and a white PET layer having a thickness of 15 μm. The L value on the surface of the translucent PET layer is 88, and L on the surface of the white PET layer. The value is 89.

(17) C layer forming film (W2):
A PET film “Teijin Tetron Film VW” (trade name) manufactured by Teijin DuPont was used. The thickness is 125 μm. This film is a laminated film comprising a translucent PET layer having a thickness of 100 μm and a white PET layer having a thickness of 25 μm. The L value on the surface of the translucent PET layer is 88, and the L value on the surface of the white PET layer is L The value is 89.

(18) C layer forming film (W3):
A white highly concealed PET film “Lumirror E20” (trade name) manufactured by Toray Industries, Inc. was used. The thickness is 100 μm. The L value on the film surface is 91.

(19) C layer forming film (W4):
A translucent PET film “Lumirror X10S” (trade name) manufactured by Toray Industries, Inc. was used. The thickness is 50 μm. The L value on the film surface is 59.

(20) D layer forming film:
A film forming machine having a T-die having a die width of 1,400 mm and a lip interval of 1.5 mm and having one extruder with a screw diameter of 65 mm is used. The extruder is vinylidene fluoride resin (manufactured by Kureha Corporation, KF Polymer). T # 1000). And the composition fuse | melted at 240 degreeC was discharged from the T die, and it was set as the thin body. Then, this thin-walled body was brought into surface contact with a cast roll whose surface temperature was controlled at 65 ° C. with an air knife and cooled and solidified to obtain a film having a thickness of 50 μm. Thickness gauge "ID-C1112C" (model name) manufactured by Mitutoyo Co., Ltd. was used to cut the film after 1 hour from the start of film production. Then, the thickness was measured at intervals of 10 mm (n = 100), and the average value was obtained. Measurement point values in the range of 20 mm from the edge of the film were removed from the average calculation.

(21) Water vapor barrier layer forming film (S1):
A transparent vapor deposition film “Tech Barrier LX” (trade name) manufactured by Mitsubishi Plastics, Inc. was used. It is a transparent film having a silica vapor deposition film on one side of a PET film, and has a thickness of 12 μm and a water vapor transmission rate (JIS K7129) of 0.2 g / (m ² · day).

(22) Water vapor barrier layer forming film (S2):
An inorganic binary vapor barrier film “Ecosia VE500” (trade name) manufactured by Toyobo Co., Ltd. was used. This is a transparent film obtained by vapor-depositing (silica / alumina) on one side of a PET film, and has a thickness of 12 μm and a water vapor permeability of 0.5 g / (m ² · day).

<Preparation of rubber-containing aromatic vinyl resin composition (I)>
Production Example 1-1
The rubber reinforced resin (A1-1), the acrylonitrile / styrene copolymer (A2-1), and the colorant were mixed by a Henschel mixer at the ratio shown in Table 1. Then, using a twin screw extruder “TEX44” (model name) manufactured by Nippon Steel Works, melt-kneading was performed at a barrel temperature of 240 ° C. to obtain a pellet-shaped thermoplastic resin composition (I-1) (Table 1). reference).

Production Examples 1-2 to 1-9:
Except having used each raw material shown in Table 1 in the ratio shown in Table 1, it carried out similarly to manufacture example 1-1, and obtained the pellet-shaped thermoplastic resin composition (I-2)-(I-9). (See Table 1).

<Preparation of rubber-containing aromatic vinyl resin composition (II)>
Production Example 2-1
The rubber-reinforced resin (A1-1), the acrylonitrile / styrene copolymer (A2-1), and the colorant (titanium oxide) were mixed at a ratio shown in Table 2 using a Henschel mixer. Then, it melt-kneaded at the barrel temperature of 240 degreeC using the Nippon Steel Works twin screw extruder "TEX44" (model name), and obtained the pellet-shaped thermoplastic resin composition (II-1) (refer Table 2). ).

Production Examples 2-2 to 2-7:
Except having used each raw material shown in Table 2 in the ratio shown in Table 2, it carried out similarly to manufacture example 2-1, and obtained the pellet-shaped thermoplastic resin composition (II-2)-(II-7). (See Table 2).

<Manufacture and evaluation of back surface protective film for solar cell (1)>
Example 1:
A multi-layer film molding machine having a T-die having a die width of 1,400 mm and a lip interval of 1.5 mm and having two extruders with a screw diameter of 65 mm is used, and each extruder contains a rubber-containing aromatic vinyl resin composition ( I-1) and a rubber-containing aromatic vinyl resin composition (II-1) were supplied. And each composition fuse | melted at 240 degreeC was discharged from the T-die, and it was set as the two-layer type thin body. Thereafter, this two-layer thin-walled body was brought into close contact with a cast roll whose surface temperature was controlled at 65 ° C. with an air knife and cooled and solidified to obtain a two-layer film having a thickness of 160 μm. Thickness gauge "ID-C1112C" (model name) manufactured by Mitutoyo Co., Ltd. was used to cut the film after 1 hour from the start of film production. Then, the thickness was measured at intervals of 10 mm (n = 100), and the average value was obtained. Measurement point values in the range of 20 mm from the edge of the film were removed from the average calculation.

  Next, the C layer forming film described in Table 3 is adhered to the surface of the B layer in the two-layer film using a polyurethane-based adhesive to create a laminated film, and the C layer in this laminated film The film for D layer formation of Table 3 was adhere | attached on the side surface using the polyurethane-type adhesive agent, and the back surface protective film for solar cells was obtained. And about this solar cell back surface protective film, various evaluation was performed and the result was written together in Table 3.

Examples 2 to 10 and Comparative Examples 1 to 4:
Using the rubber-containing aromatic vinyl resin composition (I), the rubber-containing aromatic vinyl resin composition (II), the C layer forming film, the D layer forming film, etc. shown in Tables 3 and 4 In the same manner as in Example 1, a solar cell back surface protective film was obtained. And about these back surface protection films for solar cells, various evaluation was performed and the result was written together in Table 3 and Table 4. FIG.

<Manufacture and evaluation of back surface protective film for solar cell (2)>
Example 11:
A multi-layer film molding machine having a T-die having a die width of 1,400 mm and a lip interval of 1.5 mm and having two extruders with a screw diameter of 65 mm is used, and each extruder contains a rubber-containing aromatic vinyl resin composition ( I-2) and a rubber-containing aromatic vinyl resin composition (II-2) were supplied. And each composition fuse | melted at 240 degreeC was discharged from the T-die, and it was set as the two-layer type thin body. Thereafter, this two-layer thin-walled body was brought into close contact with a cast roll whose surface temperature was controlled at 65 ° C. with an air knife and cooled and solidified to obtain a two-layer film having a thickness of 160 μm.

  Next, the C layer forming film shown in Table 5 is adhered to the surface of the B layer side in the two-layer film using a polyurethane-based adhesive to prepare a laminated film, and the C layer in this laminated film A water vapor barrier layer-forming film (R-1) was adhered to the side surface using a polyurethane-based adhesive such that the deposited film was the outer surface. Furthermore, the film for D layer formation of Table 5 was adhere | attached on the surface of the vapor deposition film in a water vapor | steam barrier layer using the polyurethane adhesive, and the back surface protective film for solar cells was obtained. And about this back surface protective film for solar cells, various evaluation was performed and the result was written together in Table 5.

Examples 12-14:
A back protective film for a solar cell was obtained in the same manner as in Example 10 except that the water vapor barrier layer forming film shown in Table 5 was used. And about this back surface protective film for solar cells, various evaluation was performed and the result was written together in Table 5.

  In the back surface protective film including the A layer, the B layer, the C layer, and the D layer, which is one embodiment of the present invention, when the light is emitted to the A layer, the appearance is excellent in dark color tone, and the photoelectric conversion efficiency Excellent in reflectivity of the light transmitted through the A layer and in the B layer. Moreover, it is excellent in the protection with respect to the heat | fever from the back surface, external force, etc. by providing D layer. In a high temperature environment, thermal deformation due to light reception or the like is suppressed, heat resistance is excellent, flame resistance is excellent, and designability and weather resistance can be maintained over a long period of time. Moreover, it is excellent in coloring property and moldability, and processability and its handleability are good. Furthermore, the adhesiveness with the member containing an ethylene / vinyl acetate copolymer is excellent. Therefore, an article provided with a support part on the D layer side, a member containing an ethylene / vinyl acetate copolymer, etc., as an article joined to the surface of the A layer side, for example, is exposed to sunlight or wind and rain for a long time. It is suitable for applications where shape stability and the like are required. Especially, it is useful as a structural member of the solar cell module which comprises the solar cell arrange | positioned on roofs, such as a house and a building, ie, a solar cell backsheet. Since this back surface protective film is excellent in flexibility, it is not dependent on the shape of the solar cell module, that is, it is arranged according to the surface shape of the filler portion filling the gaps of the solar cell elements included in the solar cell module. It is suitable for protection of solar cell elements.

  Moreover, in addition to the A layer, the B layer, the C layer, and the D layer, which are other embodiments of the present invention, further, between the A layer and the B layer, between the B layer and the C layer, and / or C In the back surface protective film having a water vapor barrier layer between the layer D and the layer D, when light is emitted to the layer A, it has an excellent dark color appearance and excellent photoelectric conversion efficiency. The light transmitted through the barrier layer is excellent in reflectivity in the B layer. Moreover, it is excellent in the protection with respect to the heat | fever from the back surface, external force, etc. by providing D layer. In a high-temperature environment, thermal deformation due to light reception or the like is suppressed, the heat resistance is excellent, the flame retardancy is excellent, and the designability and weather resistance can be maintained over a long period of time. Moreover, in any of the surface on the A layer side and the surface on the D layer side, the water vapor barrier property is excellent, the colorability and the moldability are excellent, and the workability and the handleability thereof are good. Furthermore, the adhesiveness with the member containing an ethylene / vinyl acetate copolymer is excellent. Therefore, an article provided with a support part on the D layer side, a member containing an ethylene / vinyl acetate copolymer, etc., as an article joined to the surface of the A layer side, for example, is exposed to sunlight or wind and rain for a long time. It is suitable for applications where shape stability and the like are required. Especially, it is useful as a structural member of the solar cell module which comprises the solar cell arrange | positioned on roofs, such as a house and a building, ie, a solar cell backsheet. Since this back surface protective film is excellent in flexibility, it is not dependent on the shape of the solar cell module, that is, it is arranged according to the surface shape of the filler portion filling the gaps of the solar cell elements included in the solar cell module. It is suitable for protection of solar cell elements.

1: Solar cell back surface protective film 11: A layer 12: B layer 13: C layer 14: D layer 15: water vapor barrier layer 2: solar cell module 21: surface side transparent protective member 23: surface side sealing film 25: Solar cell element 27: back side sealing film

Claims (11)

  A layer (A layer) comprising an infrared transmitting colorant mixture comprising at least two kinds of colorants and a rubber-containing aromatic vinyl resin, titanium oxide having an average primary particle size of 0.24 μm or more, and a rubber-containing aromatic vinyl resin. A layer film comprising a layer (B layer), a layer containing a saturated polyester resin (C layer), and a layer containing a fluorine-based resin (D layer), the surface on the A layer side of the laminate film When a light having a wavelength of 740 nm is radiated to the solar cell, the solar cell back surface protective film has a reflectance of 20% or more.   At least two colorants are selected from the group consisting of a red colorant and a green colorant, a purple colorant and a yellow colorant; and an orange colorant and a blue colorant The back surface protective film for solar cells according to claim 1, comprising at least one combination of coloring agents.   The back surface protective film for solar cells according to claim 1, wherein the at least two colorants are at least four colorants.   The back surface protective film for solar cells according to claim 3, wherein at least four kinds of colorants include a red colorant, a green colorant, a yellow colorant, and a purple colorant.   The back surface protective film for a solar cell according to any one of claims 1 to 4, wherein the fluororesin is a polyvinylidene fluoride resin.   The back surface for solar cells according to any one of claims 1 to 5, wherein, when light having a wavelength of 400 to 700 nm is emitted to the surface on the A layer side of the back surface protective film for solar cells, the light absorption rate is 60% or more. Protective film.   The solar cell according to any one of claims 1 to 6, wherein, when light having a wavelength of 800 to 1,400 nm is emitted to the surface on the A layer side of the back surface protective film for solar cell, the reflectance with respect to the light is 50% or more. Back surface protection film.   The back protective film for solar cells according to any one of claims 1 to 7, comprising a water vapor barrier layer as an intermediate layer of the laminated film.   The back protective film for a solar cell according to claim 8, wherein the water vapor barrier layer is a vapor-deposited film in which a film containing a metal and / or a metal oxide is formed on the surface thereof.   The back surface protective film for solar cells according to any one of claims 1 to 9, which has a thickness of 30 to 900 µm. A solar cell module comprising the solar cell back surface protective film according to any one of claims 1 to 10.

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